Added tips and tricks document to the docs folder

[robintw]

Related Issue(s): #
N/A

Description:
I came across various problems during setup of stac-fastapi. The solutions to some of these (like enabling CORS or enabling the ContextExtension) can't be enabled for everyone in the original setup, but I wanted to document how to set these up. I couldn't work out where to put the docs, so I added a 'tips and tricks' file in the docs folder - I assume this will automatically appear in the docs sidebar.

If you'd prefer this to be elsewhere, or if you disagree with any of the content, then let me know. Hopefully it will help other people who are getting started with stac-fastapi.

PR Checklist:

• Code is formatted and linted (run pre-commit run --all-files)
• Tests pass (run make test)
• Documentation has been updated to reflect changes, if applicable, and docs build successfully (run make docs)
• Changes are added to the CHANGELOG.

[robintw]

I was hoping this would appear in the left-hand menu of the docs webpage at https://stac-utils.github.io/stac-fastapi/. Does this require a manual re-build? Or did I put the file in the wrong place, or miss out a bit of configuration?