Add -f option and explanation to push after rebase

Signed-off-by: Bryan Boreham <bjboreham@gmail.com>

docs/sources/project/work-issue.md

@@ -191,9 +191,10 @@ You should pull and rebase frequently as you work.
 
 	Make sure you include your signature.
 
-8. Push any changes to your fork on GitHub.
+8. Push any changes to your fork on GitHub, using the `-f` option to
+force the previous change to be overwritten.
 
-		$ git push origin 11038-fix-rhel-link
+		$ git push -f origin 11038-fix-rhel-link
 
 
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