Dev/mip 821/microk8s observability addon documentation (#457)

Added documentation for the observability addon in microk8s.

https://team-1617704806227.atlassian.net/browse/MIP-821

kubernetes/docs/ObservabilityAddonForMicrok8s.md

+## Prometheus and Loki Installation on Microk8s
+
+### Addon installation
+
+Both the Prometheus and Loki (Log Search) are packaged inside the `observability` addon of microk8s. In order to install run the following command after setting up the microk8s cluster:
+```
+microk8s enable observability
+```
+
+### Exposing Grafana and Prometheus
+In order to expose grafana you need the following command:
+```
+microk8s kubectl port-forward -n observability service/kube-prom-stack-grafana --address 0.0.0.0 9091:80 &
+```
+In order to login to grafana, use the password provided after installation.
+
+
+In order to expose prometheus:
+```
+microk8s kubectl port-forward -n observability service/prometheus-operated --address 0.0.0.0 9090:9090 &
+```
+
+### Setting up Grafana for Node Resources Utilization
+In order to see the system resources used by your pods, after you login to grafana go to:
+```
+Dashboards -> Browse -> Kubernetes / Compute Resources / Node (Pods)
+```
+You can also use any other dashboard you prefer, for other visualizations, or make your own!
+
+
+### Setting up Log Search
+We are going to use Loki to perform log search across the federation, go to:
+```
+Explore ->
+  At the top of the page select Loki -> 
+    As label filters add "Namespace" = "default" (that will search only in exareme containers) ->
+      In the "Line Contains" field add the text to search for. ->
+        Logs from all containers will be aggregated at the bottom.
+```
+
+Example:
+
+![image](https://github.com/madgik/exareme2/assets/15667989/6e6e28bc-0363-4e33-b8a1-07ad87ef368c)
+
+
+
+### Notes
+As stated after the addon installation:
+```
+Note: the observability stack is setup to monitor only the current nodes of the MicroK8s cluster.
+For any nodes joining the cluster at a later stage this addon will need to be set up again.
+```