feat: pre-commit hook to correct spellings using codespell

[Namyalg]

Description

This PR adds a pre-commit hook to correct the spellings of commonly used words. Words related to the technical domain are not modified by codespeller

• Issue reference: Feature Request: Correct spelling errors using a pre-commit hook #190
• Peer reviewer: @HarshCasper @chicken-biryani @shubhamkarande13
• Explain the changes: A pre-commit hook has been introduced, such that each time the command git commit is run, commonly used spellings are checked for correctness in rst files only
• Dependency changes: The pre-commit hooks requires the installation of the pre-commit in the local repository
• Documentation update: The steps to install pre-commit and setup the environment are updated in the README

The following is an error reported by codespeller

The word merge is misspelled as mege, in the file https://docs.moja.global/en/master/Guidelines/DeveloperWorkflow/bots_and_integrations.html

The changes are corrected and staged as shown below

Thanks for opening the Pull Request for moja global. Happy contributing ✨