Fix structure of About files

Author: sdwheeler

reference/5.1/Microsoft.PowerShell.Core/About/about_Comment_Based_Help.md

@@ -10,6 +10,7 @@ title: about_Comment_Based_Help
 # about_Comment_Based_Help
 
 ## SHORT DESCRIPTION
+
 Describes how to write comment-based help content for functions and scripts.
 
 ## LONG DESCRIPTION

reference/5.1/Microsoft.PowerShell.Core/About/about_Environment_Variables.md

@@ -9,6 +9,7 @@ title: about_Environment_Variables
 # about_Environment_Variables
 
 ## SHORT DESCRIPTION
+
 Describes how to access and manage environment variables in PowerShell.
 
 ## LONG DESCRIPTION
@@ -24,8 +25,6 @@ programs. PowerShell creates the following environment variables:
 For full descriptions of these variables, see the
 [PowerShell environment variables][03] of this article.
 
-## LONG DESCRIPTION
-
 PowerShell can access and manage environment variables in any of the supported
 operating system platforms. The PowerShell Environment provider lets you get,
 add, change, clear, and delete environment variables in the current console.