remove includes from summary (#3349)

Author: mairaw

xml/ns-System.Collections.Immutable.xml

@@ -1,9 +1,11 @@
 <Namespace Name="System.Collections.Immutable">
   <Docs>
-    <summary>The <see cref="N:System.Collections.Immutable" /> namespace contains interfaces and classes that define immutable collections. These classes are supported starting with [!INCLUDE[net_v45](~/includes/net-v45-md.md)]. Use them to build apps that target the desktop, [!INCLUDE[win8_appstore_long](~/includes/win8-appstore-long-md.md)], [!INCLUDE[net_portable](~/includes/net-portable-md.md)] and Windows Phone 8.</summary>
+    <summary>The <see cref="N:System.Collections.Immutable" /> namespace contains interfaces and classes that define immutable collections.</summary>
     <remarks>
       <format type="text/markdown"><![CDATA[
+
 ## Remarks  
+
 With immutable collections, you can:
 
 - Share a collection in a way that its consumer can be assured that the collection never changes.