Add GitHub to release-process as a known instance (InnerSourceCommons#568)

Author: zkoppert

patterns/2-structured/release-process.md

@@ -58,6 +58,7 @@ Release notes are also a great opportunity to [praise participants](praise-parti
 ## Known Instances
 
 * Comcast (multiple projects)
+* GitHub (multiple projects)
 
 ## Authors