Missing contributing guidelines

[vil02]

Describe the bug in a sentence or two.

The target of the link: https://github.com/cloudinary/cloudinary_java/blob/43d8e9ac0c7f073017d9c4b566c9566dea95f205/README.md?plain=1#L130 does not exist.

Issue Type (Can be multiple)

[ ] Build - Can’t install or import the SDK [ ] Performance - Performance issues [ ] Behaviour - Functions aren’t working as expected (Such as generate URL) [ ] Documentation - Inconsistency between the docs and behaviour [x] Other (Specify)

[debnath003]

I would like to work on this. Can you assign it to me?

[michal-sordyl-cloudinary]

@debnath003 Thanks for PR, we will review it!