Fix issue reference syntax

Also, comment added to explain the challenge of starting the commit
message with a # character.

set-up-development-environment.md

@@ -57,8 +57,10 @@ and also work on making additions.
    $ git commit 
    ````
    Note - the commit message should have the issue number at the
-   beginning. So in this case, "I6 - Document how to create local
-   environment"
+   beginning. So in this case, "Issue #6 - Document how to create local
+   environment". Note - Depending on the editor you are using to
+   edit your commit message, you might have issues if you *start*
+   the message with a '#'.
 6. Push the changes to **your** repository:
    ````
    $ git push upstream