Code block improvements (#382)

* Use f-strings instead of .format()

* Code block language marker fixes

* Make example code blocks syntactically valid Python

* Run all python code blocks through black

https://github.com/scop/misc/blob/master/black_markdown.py

* Add some missing code block language markers

* Use shell language consistently to mark shell code blocks

* Undo folding of some example dicts

* Remove outdated OrderedDict comments per Python 3.7, replace with plain dict

docs/asyncio_working_with_async.md

@@ -16,14 +16,16 @@ To make a component async, implement an async_setup.
 
 ```python
 def setup(hass, config):
-    # Setup your component outside of the event loop.
+    """Set up component."""
+    # Code for setting up your component outside of the event loop.
 ```
 
 Will turn into:
 
 ```python
 async def async_setup(hass, config):
-    # Setup your component inside of the event loop.
+    """Set up component."""
+    # Code for setting up your component inside of the event loop.
 ```
 
 ## Implementing an async platform
@@ -31,16 +33,17 @@ async def async_setup(hass, config):
 For platforms we support async setup. Instead of setup_platform you need to have a coroutine async_setup_platform.
 
 ```python
-setup_platform(hass, config, add_entities, discovery_info=None):
-    # Setup your platform outside of the event loop.
+def setup_platform(hass, config, add_entities, discovery_info=None):
+    """Set up platform."""
+    # Code for setting up your platform outside of the event loop.
 ```
 
 Will turn into:
 
 ```python
-async def async_setup_platform(hass, config, async_add_entities,
-                               discovery_info=None):
-    # Setup your platform inside of the event loop
+async def async_setup_platform(hass, config, async_add_entities, discovery_info=None):
+    """Set up platform."""
+    # Code for setting up your platform inside of the event loop.
 ```
 
 The only difference with the original parameters is that the `add_entities` function has been replaced by the async friendly callback `async_add_entities`.
@@ -76,12 +79,15 @@ In the following example, `say_hello` will schedule `async_say_hello` and block
 ```python
 import asyncio
 
+
 def say_hello(hass, target):
     return asyncio.run_coroutine_threadsafe(
-        async_say_hello(hass, target), hass.loop).result()
+        async_say_hello(hass, target), hass.loop
+    ).result()
+
 
 async def async_say_hello(hass, target):
-    return "Hello {}!".format(target)
+    return f"Hello {target}!"
 ```
 
 ## Calling sync functions from async