Add some x-refs

docs/howto/features/storage-quota.md

@@ -1,3 +1,4 @@
+(howto:configure-storage-quota)=
 # Configure per-user storage quotas
 
 This guide explains how to enable and configure per-user storage quotas.
@@ -147,4 +148,4 @@ xfs_quota -x -c 'report -N -p'
 
 This should show us the list of directories being monitored for quota enforcement, and the current usage and quotas for each of the home directories.
 
-If a user exceeds their quota, the user's pod will not be able to start successfully. A hub admin will need to free up space in the user's home directory to allow the pod to start.
+If a user exceeds their quota, the user's pod will not be able to start successfully. A hub admin will need to free up space in the user's home directory to allow the pod to start, using [the `allusers` feature](topic:storage:allusers).

docs/topic/infrastructure/storage-layer.md

@@ -1,3 +1,4 @@
+(topic:storage)=
 # User home directory storage
 
 All users on all the hubs get a home directory with persistent storage.
@@ -71,6 +72,7 @@ This volumeMount is **NOT `readOnly`**, so admins can write to it.
 This feature comes from the [custom KubeSpawner](https://github.com/2i2c-org/infrastructure/tree/HEAD/helm-charts/basehub/values.yaml#L182) that the our community hubs use, that allows providing extra configuration for admin users only.
 ```
 
+(topic:storage:allusers)=
 #### (Optional) The `allusers` directory
 
 Can be mounted **just for admins**, showing the contents of `<hub-directory-path>/<hub-name>/`.