docs(accordion): markdown cleanup

Also rephrased the template part a bit.

Closes #4281

Author: Foxandxss

Diff for: src/accordion/docs/readme.md

@@ -2,14 +2,14 @@ The **accordion directive** builds on top of the collapse directive to provide a
 
 The body of each accordion group is transcluded into the body of the collapsible element.
 
-### Accordion Settings ###
+### Accordion Settings
 
   * `close-others` (Defaults: false) :
     Control whether expanding an item will cause the other items to close
   * `template-url` (Defaults: `template/accordion/accordion.html`) :
-    Add ability to override the template url used
+    Add the ability to override the template used on the component.
 
-### Accordion Group Settings ###
+### Accordion Group Settings
 
   * `is-disabled` <i class="glyphicon glyphicon-eye-open"></i> (Defaults: false) :
     Whether the accordion group is disabled or not.
@@ -20,7 +20,7 @@ The body of each accordion group is transcluded into the body of the collapsible
   * `panel-class` (Defaults: `panel-default`) :
     Add ability to use Bootstrap's contextual panel classes (panel-primary, panel-success, panel-info, etc...) or your own.  This must be a string.
   * `template-url` (Defaults: `template/accordion/accordion-group.html`) :
-    Add ability to override the template url used. Note that this must be a string
+    Add the ability to override the template used on the component.
 
 ### Accordion heading