Need for CONTRIBUTING.md guide in ./docs

[AryanNanda17]

Introduction or background of this discussion:

I noticed that the ianvs repository currently lacks a CONTRIBUTING.md guide specifically for documentation.

Contents of this discussion:

Adding a CONTRIBUTING.md file would provide clear instructions for contributors on how to set up Sphinx docs on their system and contribute more effectively. Therefore, I propose adding a CONTRIBUTING.md guide under the ./docs directory.
@MooreZheng @hsj576 should I go ahead with a PR and add this?

[AryanNanda17]

/kind documentation