Docs: add new FastAPI server libraries with examples

[volfpeter]

Description

I updated server-examples.md with two libraries that add HTMX support and server-side rendering to FastAPI. Both libraries are HTMX-first, and have guides and example applications.

Note: the linked Awesome Python HTMX repo doesn't seem to be maintained anymore.

Checklist

• [x] I have read the contribution guidelines
• [x] I have targeted this PR against the correct branch (master for website changes, dev for source changes)
• [x] This is either a bugfix, a documentation update, or a new feature that has been explicitly approved via an issue
• [x] I ran the test suite locally (npm run test) and verified that it succeeded