Moving Giscus critical variables to .env

[Music47ell]

I think we should move Giscus critical variables to a .env file to prevent unwanted comments like this one.

What I think happened is that someone cloned or forked this repository and tested the comment system without changing the settings inside https://github.com/timlrx/tailwind-nextjs-starter-blog/blob/master/data/siteMetadata.js causing their comment to appear in this template Discussion tab.

I propose that we do the following:

1. Move the following Giscus variables to a .env file: repo, repositoryId, category, categoryId
2. Create a .env.example file similar to this one https://github.com/leerob/leerob.io/blob/main/.env.example and add the appropriate variables.

This template is gaining a lot of attention and is increasing in popularity. Keeping the variables the way they are right now could cause more unwanted comments to appear and even spam.

I tested adding a .env file locally and it works great. I can send a PR soon if you agree with my proposal.

[timlrx]

Yes, let's do that. Noticed the unwanted comment as well 😆

[Music47ell]

PR #141 is ready for your approval.