Add documentation for hangouts and notify.hangouts components (#6044)

* Add documentation for hangouts and notify.hangouts components

* use {% configuration %}

* name is not required

* Update hangouts.markdown

remove email and password from config
add integrations description

* Update hangouts.markdown

Add notice for 2fa

* Typo

* More fixes

* Update notify.hangouts.markdown

* Update notify.hangouts.markdown

add hint to hangouts.conversations

* cleaner doc removing name option from conversations entries

source/_components/hangouts.markdown

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+---
+layout: page
+title: "Google Hangouts"
+description: "Hangouts chatbot support"
+date: 2018-08-18 20:00
+sidebar: true
+comments: false
+sharing: true
+footer: true
+logo: hangouts.png
+ha_category: Hub
+ha_release: 0.77
+---
+
+This component allows you to send messages to [Google Hangouts](http://hangouts.google.com) conversations, as well as to react to messages in conversations. Reacting to commands is accomplished by firing an event when one of the configured commands is triggered.
+
+## {% linkable_title Setup the component via the frontend %}
+
+Menu: *Configuration* -> *Integrations*
+  
+Fill the form:
+* Your **Google Mail Address** and **Password**
+* If needed, you will be asked for a 2-factor authorization token
+
+**IMPORTANT:** If you secured your account with 2 factor authorization: Only verification by app or SMS are supported. There is no support for verification by prompt on your phone.
+
+The authentication token will be generated and stored internally.
+
+```yaml
+# Example configuration.yaml entry
+hangouts:
+  commands:
+    - word: testword
+      conversations:
+        - id: CONVERSATION_ID1
+        - id: CONVERSATION_ID2
+    - expression: "My name is (?P<name>.*)"
+      name: introduction
+```
+{% configuration %}
+commands:
+  description: "A list of commands that the bot should listen for. If a command is triggered (via its *word* or *expression*, see below), an event is fired that you can handle using automations. Every command consists of these possible configuration options:"
+  required: false
+  type: map
+  default: empty
+  keys:
+    word:
+      description: "Specifies a word that the bot should listen for. If you specify 'my_command' here, the bot will react to any message starting with 'my_command'."
+      required: false
+      type: string
+    expression:
+      description: "Specifies a regular expression (in python regexp syntax) that the bot should listen to. The bot will react to any message that matches the regular expression."
+      required: false
+      type: string
+    name:
+      description: "The name of the command. This will be an attribute of the event that is fired when this command triggers."
+      required: true
+      type: string
+    conversations:
+      description: "A list of conversations that the bot should listen for this command in. If this is not given, all conversations are used."
+      required: false
+      type: [map]
+      default: empty
+      keys:
+        id:
+          description: "Specifies the id of the conversation. *The conversation id can be obtained from the `hangouts.conversations` entity.*"
+          required: true
+          type: string
+{% endconfiguration %}
+
+The conversations has to be precreated, the conversation id can be obtained from the `hangouts.conversations` entity. Make sure to use quotes around the conversation id or alias to escape special characters (`!`, and `#`) in YAML.
+
+### {% linkable_title Event Data %}
+
+If a command is triggered, a `hangouts_command` event is fired. The event contains the name of the command in the `command` field.
+
+If the command is a word command, the `data` field contains a list of the command's arguments, i.e., everything that stood behind the word, split at spaces. If the command is an expression command, the `data` field contains the [group dictionary](https://docs.python.org/3.6/library/re.html?highlight=re#re.match.groupdict) of the regular expression that matched the message.
+
+There are these additional fields: `conversation_id`, `user_id` and `user_name`.
+
+### {% linkable_title Comprehensive Configuration Example %}
+
+```yaml
+# The Hangouts component
+hangouts:
+  commands:
+    - word: testword
+      conversations:
+        - name: "someothertest"
+    - expression: "My name is (?P<name>.*)"
+      name: introduction
+
+automation:
+  - alias: 'React to !testword'
+    trigger:
+      platform: event
+      event_type: hangouts_command
+      event_data:
+        command: testword
+    action:
+      service: hangouts.send_message
+      data_template:
+        target: 
+          - name: "hasstest"
+        message: 
+          - text: 'It looks like you wrote testword'
+  - alias: 'React to an introduction'
+    trigger:
+      platform: event
+      event_type: hangouts_command
+      event_data:
+        command: introduction
+    action:
+      service: hangouts.send_message
+      data_template:
+        target: 
+          - id: '{{ trigger.event.data.conversation_id}}'
+        message: 
+          - text: "Hello {{ trigger.event.data.data.name }}"
+
+```
+
+This configuration will:
+- Listen for "testword" in the room "someothertest" (and only) there. 
+  If such a message is encountered, it will answer with "It looks like you wrote testword" into the "hasstest" conversation.
+- Listen in all conversations for any message matching "My name is (any name)" and answer with "Hello (the given name)" into the same conversation.

source/_components/notify.hangouts.markdown

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+---
+layout: page
+title: "Google Hangouts"
+description: "Instructions on how to add Google Hangouts notifications to Home Assistant."
+date: 2018-08-18 20:00
+sidebar: true
+comments: false
+sharing: true
+footer: true
+logo: hangouts.png
+ha_category: Notifications
+ha_release: 0.77
+---
+
+
+The `hangouts` platform allows you to deliver notifications from Home Assistant to [Google Hangouts](http://hangouts.google.com) conversations. Conversations can be both direct as well as group chats.
+
+## {% linkable_title Configuration %}
+
+To enable Hangouts notifications in your installation, you first need to configure
+the [Hangouts component](/components/hangouts/). Then, add the following to your `configuration.yaml` file:
+
+```yaml
+# Example configuration.yaml entry  
+notify:
+  - name: NOTIFIER_NAME
+    platform: hangouts
+    default_conversations:
+      - id: CONVERSATION_ID1
+      - id: CONVERSATION_ID2
+```
+
+{% configuration %}
+name: 
+  description: "Setting the optional parameter `name` allows multiple notifiers to be created. The default value is `notify`. The notifier will bind to the service `notify.NOTIFIER_NAME`."
+  required: false
+  type: string
+default_conversations:
+  description: "The conversations all messages will be sent to, when no other target is given."
+  required: true
+  type: [map]
+  keys:
+    id:
+      description: "Specifies the id of the conversation. *The conversation id can be obtained from the `hangouts.conversations` entity.*"
+      required: true
+      type: string
+{% endconfiguration %}
+
+The conversations has to be precreated, the conversation id can be obtained from the `hangouts.conversations` entity. Make sure to use quotes around the conversation id or alias to escape special characters (`!`, and `#`) in YAML.
+
+To use notifications, please see the [getting started with automation page](/getting-started/automation/).
+