RFR: 202: git-pr create should use a proper Markdown file

[Erik Helin]

Hi all,

please review this patch that updates `git pr create` to show a valid Markdown
file. The instructions have been moved into HTML comments looking like the
following:

 
 
 
 
 
 
 
 
 
 
 
 

I also took the opportunity to tweak the message a bit. Furthermore I added the
status for each commit so that it is easy to see changed files and also added a
link to an eventual issue. Personally I think the end result turned out quite
nice.

Thanks,
Erik

## Testing
- [x] Manual testing of `git pr create`

-------------

Commits:
 - 1633065c: skara-202

Changes: https://git.openjdk.java.net/skara/pull/329/files
 Webrev: https://webrevs.openjdk.java.net/skara/329/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/SKARA-202
  Stats: 52 lines in 1 file changed: 36 ins; 3 del; 13 mod
  Patch: https://git.openjdk.java.net/skara/pull/329.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/329/head:pull/329

PR: https://git.openjdk.java.net/skara/pull/329