What is a recipe ?

- [x] I read [the conda-forge documentation](https://conda-forge.org/docs/user/introduction.html#how-can-i-install-packages-from-conda-forge) and could not find the solution for my problem there.

### Issue:
Throughout the conda-forge documentation, there is a mention of the word recipes, How to add a recipe, how to update a recipe,
But no mention about what is a recipe for packages, in my view there should be some sort of small introduction about what is a recipe and it can be added at the homepage.