[Docs] Clarify node-labels are additive or destructive

docs/src/charm/howto/install-custom.md

@@ -6,6 +6,7 @@ configuration options.
 ## What you'll need
 
 This guide assumes the following:
+
 -  You have Juju installed on your system with your cloud credentials
 configured and a controller bootstrapped
 - A Juju model is created and selected
@@ -35,13 +36,16 @@ k8s:
   dns-cluster-domain: "cluster.local"
   dns-upstream-nameservers: "8.8.8.8 8.8.4.4"
 
-  # Add custom node labels
-  node-labels: "environment=production zone=us-east-1"
+  # Add/Remove custom node labels
+  # Using <key>=<value> one can ensure the label is added to all the nodes of this application
+  # Using <key>=-       one can ensure the label is removed from all the nodes of this application
+  node-labels: "environment=production zone=us-east-1 node-role.kubernetes.io/worker=-"
 
   # Configure local storage
   local-storage-enabled: true
   local-storage-reclaim-policy: "Retain"
 ```
+
 You can find a full list of configuration options in the
 [charm configurations] page.
 

docs/src/charm/reference/index.md

@@ -16,6 +16,7 @@ charms
 proxy
 architecture
 charm-configurations
+troubleshooting
 Community <community>
 
 ```

docs/src/charm/reference/troubleshooting.md

@@ -0,0 +1,77 @@
+# Troubleshooting
+
+This page provides techniques for troubleshooting common {{product}}
+issues dealing specifically with the charm
+
+
+## Adjusting kubernetes node labels
+
+### Problem
+
+Control Plane or Worker nodes are automatically marked with a label that is unwanted. 
+
+For example, the control-plane node may be marked with both control-plane and worker roles
+
+```
+node-role.kubernetes.io/control-plane=
+node-role.kubernetes.io/worker=
+```
+
+### Explanation
+
+Each kubernetes node comes with a set of node labels enabled by default. The k8s charm defaults with both 
+control-plane and worker role labels, while the worker node only has a role label.
+
+For example, consider the following simply deployment with a worker and a control-plane
+```sh
+$ sudo k8s kubectl get nodes
+NAME            STATUS   ROLES                  AGE     VERSION
+juju-c212aa-1   Ready    worker                 3h37m   v1.32.0
+juju-c212aa-2   Ready    control-plane,worker   3h44m   v1.32.0
+```
+
+
+### Solution
+
+Adjusting the roles (or any label) be executed by adjusting the applications' configuration of `node-labels`
+
+To add another node label:
+
+```sh
+current=$(juju config k8s node-labels)
+if [[ $current == *" label-to-add="* ]]; then
+   # replace an existing configured label
+   updated=${current//label-to-add=*/}
+   juju config k8s node-labels="${updated} label-to-add=and-its-value"
+else
+   # specifically configure a new label
+   juju config k8s node-labels="${current} label-to-add=and-its-value"
+fi
+```
+
+To remove a node label which was added by default
+
+```sh
+current=$(juju config k8s node-labels)
+if [[ $current == *" label-to-remove="* ]]; then
+   # remove an existing configured label
+   updated=${current//label-to-remove=*/}
+   juju config k8s node-labels="${updated}"
+else
+   # remove an automatically applied label
+   juju config k8s node-labels="${current} label-to-remove=-"
+fi
+```
+
+#### Node Role example
+
+To remove the worker node-rule on a control-plane:
+
+```sh
+juju config k8s node-labels="node-role.kubernetes.io/worker=-"
+```
+
+
+
+<!-- LINKS -->
+