Remove Open from GitHub... from File > Open menu

Remove this command from the `File > Open` menu until have a proper UI
to show the user.

Author: jcansdale

src/GitHub.VisualStudio/GitHub.VisualStudio.vsct

@@ -341,9 +341,11 @@
     </CommandPlacement>
 
     <!-- Open from GitHub command -->
+    <!-- Removing from `File > Open` menu until we have a proper UI
     <CommandPlacement guid="guidGitHubCmdSet" id="openFromUrlCommand" priority="0x0100">
       <Parent guid="guidSHLMainMenu" id="IDG_VS_FILE_OPENSCC_CASCADE"/>
     </CommandPlacement>
+    -->
 
     <!-- Add Connection (Team Explorer) command -->
     <CommandPlacement guid="guidGitHubCmdSet" id="addConnectionCommand" priority="0x0100">