Update release-process.md

I would like to suggest posting tweet to become part of the release process.

[skip ci] Closes GH-5144

Author: ruudboon

docs/release-process.md

@@ -338,6 +338,9 @@
     php-announce@ is its own completely separate email. This is to make sure
     that replies to the announcement on php-general@ or internals@ will not
     accidentally hit the php-announce@ mailinglist.
+    
+11. Post tweet with release announcement and link to news article on php.net 
+    ([@official_php](https://twitter.com/official_php))  
 
 ## Re-releasing the same version (or -pl)