Optimize issue workflow for new contributors

[sypets]

• Add new label "good first issue", use TYPO3 color: #f49800 (use same in all TYPO3 documentation repos)
• Add some new issues that are actually "good first issues" and mark them
• link to this from "How you can help"

see https://help.github.com/articles/helping-new-contributors-find-your-project-with-labels/

[sypets]

Problem is, Github is a little fuzzy about labels "good first issue" and "help wanted" (and you can use this any way you want, but I think we can stick to best practices that people can inuitively understand and use correctly.)

See also messages you get on Issues tab in some projects:

• "Issues labeled help wanted or good first issue can be good first contributions." (https://github.com/symfony/symfony-docs/issues)

So it looks like you can use either "help wanted" or "good first issue", but I think "good first issue" is much clearer and I have used "help wanted" for things where help was wanted and which weren't necessarily good first issue.

Am proposing this: Use "good first issues" for good first issues for new contributors. Use "help wanted" only sparingly, because unclear and ambivalent.