Adding gh-best-practices-template

[jlcanovas]

This contribution adds https://github.com/jlcanovas/gh-best-practices-template, a template repository for helping others to follow the best practices when developing GitHub projects. It includes best practices for issues and pull requests, but also other dimensions such as governance or security. For this reason, I've created a new category.

Please ensure your pull request adheres to the following guidelines:

• Use the following format: * [owner/repo](link)
• Link additions should be added to the bottom of the relevant category.
• New categories or improvements to the existing categorization are welcome.
• Search previous suggestions before making a new one, as yours may be a duplicate.
• Sort by alphabetical order

Thanks for contributing!