Fix typo and spelling inconsistency in CONTRIBUTING.md

Fix spellings of GitHub

Remove unnecessary changes

Fix GitHub spelling on doc/translation_process.md

contrib/devtools/README.md

@@ -125,7 +125,7 @@ check or whatever).
 
 This means that there are no potential race conditions (where a
 pullreq gets updated while you're reviewing it, but before you click
-merge), and when using GPG signatures, that even a compromised github
+merge), and when using GPG signatures, that even a compromised GitHub
 couldn't mess with the sources.
 
 Setup