Standardized formatting of CLI reference commands

Command name should be a H1

Only Description, Examples, and Related Commands should be H2

Changed 'Related information' heading to 'Related commands' since 99% it is only linking commands

Added some examples where relevant

Signed-off-by: Misty Stanley-Jones <misty@docker.com>

docs/reference/commandline/plugin_enable.md

@@ -25,9 +25,12 @@ Options:
       --timeout int   HTTP client timeout (in seconds)
 ```
 
+## Description
+
 Enables a plugin. The plugin must be installed before it can be enabled,
 see [`docker plugin install`](plugin_install.md).
 
+## Examples
 
 The following example shows that the `sample-volume-plugin` plugin is installed,
 but disabled:
@@ -52,7 +55,7 @@ ID                  NAME                             TAG                 DESCRIP
 69553ca1d123        tiborvass/sample-volume-plugin   latest              A test plugin for Docker   true
 ```
 
-## Related information
+## Related commands
 
 * [plugin create](plugin_create.md)
 * [plugin disable](plugin_disable.md)