[Docs] Add a single-point starter guide for contributors

[p-wysocki]

Details:

• Add a single point of entry into OpenVINO documentation
• The document guides new OpenVINO contributors from cloning the repository all the way to submitting a Pull Request
• The links allow for quick access to all (?) important documentation starting points for each component

TODO

• I believe we should simplify CONTRIBUTING.md, CONTRIBUTING_ROADMAP.md, get_started.md and so on, preferably merge into one
• "Roadmap" may be a confusing name, this document may require name change

Tickets:

• N/A

[jiwaszki]

Would it make sense to also provide short tutorial/link on how to use git? It doesn't need to be external one, we can redirect to our internal one -- something similar to this: https://numpy.org/doc/stable/dev/index.html#development-process-summary

[p-wysocki]

Good point, from what I've seen a great deal of contributors are not familiar with working with forks. I'll think about how to deal with that, a guide on working with many remotes and forking tailored specifically for OV might be a good idea.

[mitruska]

As we discussed, it's worth to consider a FAQ (Frequently Asked Questions) section.
It could be supported by links to the already existing useful comments from reviewers/maintainers for issues, where such question was already resolved.

[kblaszczak-intel]

That is a very cool addition! I've added tiny language adjustments but they are barely relevant.

[p-wysocki]

@jiwaszki @mitruska I'll address your suggestions in a separate PR, I really want to merge this one ASAP. Just letting you know that I did not forget about them. :)

[mlukasze]

please add ticket ID which you will use to follow up

[p-wysocki]

@mlukasze done.

As we discussed, it's worth to consider a FAQ (Frequently Asked Questions) section.
It could be supported by links to the already existing useful comments from reviewers/maintainers for issues, where such question was already resolved.

Continued in 127561.

Would it make sense to also provide short tutorial/link on how to use git?

Continued in 127562.