Gallery of toy recipes that implement "known conda-build patterns"

### Where should the content be added?

This could be worth its own section

### What should be added?

The idea is to have a set of recipes that implement known patterns that might be not obvious. One can always use the new search Github feature to look for similar examples, but they are often too complex (several patterns at once) to infer the known bits quickly.

Having single-pattern recipes (even if they do not really build real packages) could be a useful resource for users learning how to create recipes for conda-forge.

### Additional information

Inspired by conversation in [this Matrix thread](https://matrix.to/#/!SOyumkgPRWoXfQYIFH:matrix.org/$1677700232142KtYJW:gitter.im?via=matrix.org&via=gitter.im&via=staffchat.ethz.ch).