Merge pull request #1488 from github/fixes/1463-release-notes-link

Add links to release notes in vsixmanifest.

Author: shana

src/GitHub.VisualStudio/source.extension.vsixmanifest

@@ -7,6 +7,7 @@
     <PackageId>GitHub.VisualStudio</PackageId>
     <MoreInfo>https://visualstudio.github.com</MoreInfo>
     <License>LICENSE.txt</License>
+    <ReleaseNotes>https://visualstudio.github.com/release-notes.html</ReleaseNotes>
     <Icon>Resources\[email protected]</Icon>
     <PreviewImage>Resources\preview_200x200.png</PreviewImage>
     <Tags>GitHub;git;open source;source control;branch;pull request;team explorer;commit;publish</Tags>