Initial glossary (#3568)

* Initial glossary

* Allow markdown in the description

source/_data/glossary.yml

@@ -0,0 +1,17 @@
+- topic: Platform
+  description: A platform makes the connection to a specific software or hardware platform. The `pushbullet` platform works with the service from pushbullet.com.
+- topic: Component
+  description: "The components provide the core logic for the functionality in Home Assistant. Like `notify` provides sending notifications."
+- topic: Service
+  description: "[Services](/docs/scripts/service-calls/) are called to perform actions."
+- topic: Event
+  description: When somethings happen.
+- topic: Entity
+  description: An entity is the representation of a single device, unit or web service.
+- topic: Device
+  description: "Usually this is a physical unit which can do or observe something."
+- topic: hass
+  description: "Often used abbreviation for Home Assistant."
+- topic: Discovery
+  description: The automatic setup of zeroconf/mDNS and uPnP devices after they are discovered.
+

source/_docs/glossary.markdown

@@ -0,0 +1,20 @@
+---
+layout: page
+title: "Glossary"
+description: "Home Assistant's Glossary."
+date: 2017-10-08 08:30
+sidebar: true
+comments: false
+sharing: true
+footer: true
+---
+
+{% assign entries = site.data.glossary | sort: 'topic'  %}
+
+<ul>
+{% for entry in entries %}
+  <li>
+      <b>{{ entry.topic }}</b>: {{ entry.description | markdownify }}
+  </li>
+{% endfor %}
+</ul>

source/_includes/asides/docs_navigation.html

@@ -3,7 +3,8 @@
     <h1 class="title delta">Topics</h1>
     <ul class='divided sidebar-menu'>
       <li>
-        <b>{% active_link /faq/ FAQ %}</b>
+        <b>{% active_link /faq/ FAQ %}</b> | 
+        <b>{% active_link /docs/glossary/ Glossary %}</b>
       </li>
       <li>
         <b>{% active_link /docs/installation/ Installation %}</b>