RFR: SKARA-725: Rename git-pr-reviewer --add to git-pr-reviewer --credit [v2]

[Kartik Ohri]

> Hi!
> The patch renames the add option to the credit in accordance with the change in the `/reviewer` command on OpenJDK Github bot.
> 
> I was unable to find any related documentation that should reflect  this change. If something needs to be updated, kindly point me to it and I'll do the needful changes.
> 
> Thanks.
> Regards,
> Kartik

Kartik Ohri has updated the pull request incrementally with one additional commit since the last revision:

  Improve helptext for git-pr-reviewer --credit
  
  Co-authored-by: Erik Duveblad <erik.helin at oracle.com>

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

Changes:
  - all: https://git.openjdk.java.net/skara/pull/938/files
  - new: https://git.openjdk.java.net/skara/pull/938/files/e6dfcc8c..f9b5ce90

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=skara&pr=938&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=skara&pr=938&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/skara/pull/938.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/938/head:pull/938

PR: https://git.openjdk.java.net/skara/pull/938