Create a Best Practices File

[OmarRamoun]

🟡 Changes Required

• Add a best_practices.md file that contains all best practices for topics learned in the intro_to_gh.md file.

[OmarRamoun]

@MrRamoun will handle this.

[OmarRamoun]

➕ please, add contents of these links to the best practices file.

• 🔗 link1: about PRs