[CCI] Update Contributing guide - help newers to make first PR

[Nicksqain]

Note: issue to speed up the entry threshold of the contribution process

Description:

This markdown file should help all new contributors. And should describe the whole process:
from introduction to the first pulll-request.

And describes issues such as:

• How to work with Git:

  • How to create commits
  • How to create PRs

[dblock]

We have a lot of getting started information in https://github.com/opensearch-project/OpenSearch/blob/main/DEVELOPER_GUIDE.md. I would just add to that. For things that aren't OpenSearch specific, feel free to include external links, e.g. I usually share https://gist.github.com/Chaser324/ce0505fbed06b947d962 with new contributors.

[peternied]

I don't think this issue is part of this repository's responsibilities - otherwise we'd have detailed guides for how REST APIs work, how the JVM functions, etc. If there was such a contribution guide - I don't think it should be written by someone that isn't already a contributor to the project so I've removed the 'good first issue' label.

I'm going to close this issue since it seems out of scope - there are other places [1] where this kind of tutorial might be very useful, consider looking into other parts of the OpenSearch project such as its project website repo or the .github repository that covers the broad practices and principles of the OpenSearch project's GitHub footprint.

• [1] A [short] guide for developers that are interested in contributing and trying to figure out where to start documentation-website#4939