[FEATURE] Update `CONTRIBUTING.md`

[dev-shetty]

Currently, the contributing file is not that clear, just review it once and tell the new contributor how to contribute to the project.
This should include the following points, along with installing the project locally and setting it up.

• Where to put the new snippet, which is inside the UI Snippets folder
• Add their new snippet to the code pen.
• Add an image as well which is needed for the UI.
• Add about it in the snippets.json file so we can render it in the UI.

[SuryaCreatX]

Can you assign me this issue?

[dev-shetty]

Yeah sure!
Any queries feel free to ask...

[himanchal08]

i would like to work on this issue it seems doable
i will try my best to implement it

[dev-shetty]

@himanchal08 this issue has already been assigned, try to contribute a new Snippet or raise an issue if you find any changes in the project.