Add CONTRIBUTING.md file to the repository

[Ayush9026]

Description:

To enhance the contribution process and provide clear guidelines for new and existing contributors, we need to add a CONTRIBUTING.md file to the theupdateframework.io repository. This file will outline the steps for contributing, the code of conduct, how to report issues, and how to submit pull requests.

[Ayush9026]

/assign @Ayush9026 i will solve this.