Fix SpecialFiles.ProgramFiles docs to match the actual implementation. (#4187)

* Update x86 system -> x86 process

* ProgramFiles return x86 folder when it's run on a x86 process, regardless of the system architecture

* Apply suggestions from code review

Co-authored-by: Jan Kotas <jkotas@microsoft.com>

Co-authored-by: Jan Kotas <jkotas@microsoft.com>

Author: Gnbrkm41

xml/System/Environment+SpecialFolder.xml

@@ -465,7 +465,7 @@
       <Docs>
         <summary>The directory for components that are shared across applications.  
 
- To get the x86 common program files directory on a non-x86 system, use the <see cref="F:System.Environment.SpecialFolder.ProgramFilesX86" /> member.</summary>
+ To get the x86 common program files directory in a non-x86 process, use the <see cref="F:System.Environment.SpecialFolder.ProgramFilesX86" /> member.</summary>
       </Docs>
     </Member>
     <Member MemberName="CommonProgramFilesX86">
@@ -1356,7 +1356,7 @@
       <Docs>
         <summary>The program files directory.  
 
- On a non-x86 system, passing <see cref="F:System.Environment.SpecialFolder.ProgramFiles" /> to the <see cref="M:System.Environment.GetFolderPath(System.Environment.SpecialFolder)" /> method returns the path for non-x86 programs. To get the x86 program files directory on a non-x86 system, use the <see cref="F:System.Environment.SpecialFolder.ProgramFilesX86" /> member.</summary>
+ In a non-x86 process, passing <see cref="F:System.Environment.SpecialFolder.ProgramFiles" /> to the <see cref="M:System.Environment.GetFolderPath(System.Environment.SpecialFolder)" /> method returns the path for non-x86 programs. To get the x86 program files directory in a non-x86 process, use the <see cref="F:System.Environment.SpecialFolder.ProgramFilesX86" /> member.</summary>
       </Docs>
     </Member>
     <Member MemberName="ProgramFilesX86">