Add preliminary docs for recipe metadata scores

Closes #113

docs/recipes/index.md

@@ -15,6 +15,65 @@ It aims to be a helpful place to understand the status of apps, who is taking ca
 
 The recipe catalogue is available on [recipes.coopcloud.tech](https://recipes.coopcloud.tech/).
 
+## Status / features / scoring
+
+Each recipe README has a "metadata" section, to help communicate the overall status of the recipe, and which features are supported. Here's an example, from [the Wordpress recipe](https://git.coopcloud.tech/coop-cloud/wordpress/):
+
+```
+<!-- metadata -->
+
+* **Category**: Apps
+* **Status**: 3, stable
+* **Image**: [`wordpress`](https://hub.docker.com/_/wordpress), 4, upstream
+* **Healthcheck**: Yes
+* **Backups**: Yes
+* **Email**: 3
+* **Tests**: 2
+* **SSO**: No
+
+<!-- endmetadata -->
+```
+
+Currently, recipe maintainers need to update the scores in this section manually. The specific meanings of the scores are:
+
+### Status (overall score)
+
+- 5: everything in 4 + Single-Sign-On
+- 4: upstream image, backups, email, healthcheck, integration testing
+- 3: upstream image, missing 1-2 items from 4
+- 2: missing 3-4 items from 4 or no upstream image
+- 1: alpha
+
+### Image
+
+- 4: official upstream image
+- 3: semi-official / actively-maintained image
+- 2: 3rd-party image
+- 1: our own custom image
+
+### Email
+
+- 3: automatic (using environment variables)
+- 2: mostly automatic
+- 1: manual
+- 0: none
+- N/A: app doesn't send email
+
+### CI
+
+- 3: as 2, plus healthcheck
+- 2: auto secrets + networks
+- 1: basic deployment using `stack-ssh-deploy`, manual secrets + networks
+- 0: none
+
+### Single-Sign-On
+
+- 3: automatic (using environment variables)
+- 2: mostly automatic
+- 1: manual
+- 0: none
+- N/A: app doesn't support SSO
+
 ## Wishlist
 
 If you'd like to see a new recipe packaged, make a request on the [recipes-wishlist](https://git.coopcloud.tech/coop-cloud/recipes-wishlist) repository issue tracker.