Follow guidance for git tagging in contribution docs

[elenatanasoiu]

Adding two things:

• A bit more detail on how to add a tag and how to delete a badly named one
• Switch to the official way of sharing tags according to the git docs ¹

Checklist

• CHANGELOG.md has been updated to incorporate all user visible changes made by this pull request.
• Issues have been created for any UI or other user-facing changes made by this pull request.
• [Maintainers only] If this pull request makes user-facing changes that require documentation changes, open a corresponding docs pull request in the github/codeql repo and add the ready-for-doc-review label there.

Footnotes

1. https://git-scm.com/book/en/v2/Git-Basics-Tagging ↩

[shati-patel]

Thanks for updating this and being explicit about how tagging works 🤗 🏷️

Just a minor comment from me 💭

[sampart]

Folk can also do this via https://github.com/github/vscode-codeql/releases/new. I've not tested on this repo, but on others I've found that creating a tag this way still triggers the necessary build steps. It may not be worth including, but I thought I'd mention it.

[elenatanasoiu]

Thanks @sampart! It's not 100% clear to me if you can create a "draft" release via that link so I've chosen to stick with the flow we already have.

[shati-patel]

Thanks! LGTM 🚀