Mobu: update docs about running notebooks in all dirs

docs/applications/mobu/configuring.rst

@@ -77,16 +77,21 @@ Here is a more complex example that runs a set of notebooks as a test:
          options:
            repo_url: "https://github.com/lsst-sqre/system-test.git"
            repo_branch: "prod"
+           exclude_dirs: ["some/experiment/dir", "another/dir"]
            max_executions: 1
          restart: true
 
 Here, note that the UID and primary GID for the user are specified, so this example will work in deployments that do not use Firestore and synthesized user private groups.
 
-This uses the business ``NotebookRunner`` instead, which checks out a Git repository and runs all notebooks at the top level of that repository.
+This uses the business ``NotebookRunner`` instead, which checks out a Git repository and runs all notebooks in that repository, at the top level and any directories and subdirectories.
+
 The repository URL and branch are configured in ``options``.
 ``options.max_executions: 1`` tells mobu to shut down and respawn the pod after each notebook.
 This exercises pod spawning more frequently, but does not test the lab's ability to run a long series of notebooks.
 One may wish to run multiple flocks in a given environment with different configurations for ``max_executions``.
+``options.exclude_dirs`` tells mobu to not excecute any notebooks in those directories or any descendant directories.
+Those directories are relative to the repo root.
+
 These notebooks need more scopes, so those scopes are specified.
 
 Here is a different example that runs multiple monkeys in a flock: