📖 [Docs] Supported extensions (OLM v1 constraints/limitations)

Closes operator-framework#984

docs/concepts/supported-extensions.md

@@ -0,0 +1,19 @@
+## Supported extensions
+
+Currently, OLM v1 supports installing cluster extensions that meet the following constraints:
+
+* The extension supports installation via the `AllNamespaces` install mode.
+* The extension does not use webhooks.
+* The extension does not declare dependencies using the any of  following file-based catalog properties:
+
+** `olm.gvk.required`
+** `olm.package.required`
+** `olm.constraint`
+
+When you install an extension, the bundle validation process in OLM v1 runs checks against these constraints. If you try to install an extension that has one of these constraints, an error message is printed in the cluster extension conditions.
+
+!!! important
+
+Additionally, OLM v1 does not support the `OperatorConditions` API introduced in legacy OLM.
+
+Currently, there is no testing to implemented to test for this constraint at install time. Most extensions that rely on this API fail at start up time, but some might fail during reconcilation. 

mkdocs.yml

@@ -11,6 +11,8 @@ repo_url: https://github.com/operator-framework/operator-controller
 nav:
   - Home: 'index.md'
   - Components: 'components.md'
+  - Concepts:
+    - Supported extensions: 'concepts/supported-extensions.md'
   - Tasks:
     - Adding a catalog of extensions: 'Tasks/adding-a-catalog.md'
     - Finding extensions to install: 'Tasks/exploring-available-packages.md'