Update pipeline.py --> recipe.py in README

[cisaacstern]

This PR addresses one aspect of the broader work discussed in #32. Motivated by @paigem's question in #56 (comment).

One thing I remain unclear on, is whether or not <Your recipe name> is the correct way to describe the name of the directory we want contributors to add in their PRs? Perhaps this should instead be something like, <Your feedstock name>?

@sharkinsspatial, do you know what will happen with these directories when they are merged? I believe, following conda-forge's example, they will become standalone repos within the pangeo-forge org? I feel like this is may be in an ADR somewhere, but not sure which one, and either way wanted to take the opportunity to start a conversation about merging some recipe PR's.

[sharkinsspatial]

@cisaacstern The proposed Github actions flow is covered in this ADR. Your take is correct that upon merging, each meta.yaml will be used to generate a new feedstock repository. I agree that <Your feedstock name > may be a more appropriate terminology, especially as the meta.yaml may be referencing multiple recipes.

I had been holding on this next block of work as given the issues outlined in pangeo-forge/pangeo-forge-recipes#151, none of our PRs could pass the our recipe test workflow but with the 0.4.0 release we should be able to run tests for pruned recipes. @CiaranEvans and I need to undertake the following...

1. Release a new bakery image using 0.4.0.
2. Update pangeo-forge-prefect for the recipe class signature changes introduced by 0.4.0.
3. Include the recipe pruning usage for testing described in Add copy_pruned() method to XarrayZarrRecipe pangeo-forge-recipes#139 (review)
4. Build the template repo and Github action for spinning out a new feedstock repository when a PR is merged in `staged-recipes.

I'd like to target having all this in place prior to our call next week (I'll be out traveling on Friday). I believe some of the existing PRs in staged-recipes may need modification to change their use of FilePattern but I'll let @TomAugspurger weigh in on this.

[cisaacstern]

Merging these (presumably uncontroversial) changes and migrating the remaining conversion to #58.

The README will need more work, but hopefully this will help new contributors avoid some terminology confusion.