We need to come up with some standard for documenting the built-in extension points in Blue Ocean. While initially most will probably be <ExtensionPoint> components in the the react tree, some (like for example routing) may be either plain functions, or objects. Ideally we would want to be able to find and extract documentation for these, as well as ideally providing a warning if an undocumented (or misspelled) extensionpoint is mapped in a plugin's jenkins-js-extension.yaml file.