Add MAAS infrastructure tab for CAPI tutorial (#568)

Add MAAS infrastructure tab for CAPI tutorial

---------

Co-authored-by: Louise K. Schmidtgen <louise.schmidtgen@canonical.com>
Co-authored-by: Etienne Audet-Cobello <etienne.audet-cobello@canonical.com>
Co-authored-by: Nick Veitch <nick.veitch@canonical.com>

docs/src/capi/tutorial/getting-started.md

@@ -94,7 +94,56 @@ export AWS_B64ENCODED_CREDENTIALS=$(clusterawsadm bootstrap credentials encode-a
 ```
 
 You are now all set to deploy the AWS CAPI infrastructure provider.
+````
+
+````{group-tab} MAAS
+Start by setting up environment variables to allow access to MAAS:
+
+```
+export MAAS_API_KEY="<maas-api-key>"
+export MAAS_ENDPOINT="http://<maas-endpoint>/MAAS"
+export MAAS_DNS_DOMAIN="<maas-dns-domain>"
+```
+The MAAS infrastructure provider uses these credentials to deploy machines,
+create DNS records and perform various other operations for workload clusters.
+
+```{warning}
+The management cluster needs to resolve DNS records from the MAAS domain, 
+therefore it should be deployed on a MAAS machine.
+```
+
+Define further environment variables for the machine image and minimum compute
+resources of the control plane and worker nodes:
+
+```
+export CONTROL_PLANE_MACHINE_MINCPU="1"
+export CONTROL_PLANE_MACHINE_MINMEMORY="2048"
+export CONTROL_PLANE_MACHINE_IMAGE="ubuntu"
+
+export WORKER_MACHINE_MINCPU="1"
+export WORKER_MACHINE_MINMEMORY="2048"
+export WORKER_MACHINE_IMAGE="ubuntu"
+```
+
+```{note}
+The minimum resource variables are used to select machines with resources more
+than or equal to the provided values.
+```
+
+Optional environment variables can be defined for specifying resource pools
+and machine tags:
+
+```
+# (optional) Configure resource pools for control plane and worker machines
+# export CONTROL_PLANE_MACHINE_RESOURCEPOOL="kvm-pool"
+# export WORKER_MACHINE_RESOURCEPOOL="bare-metal-pool"
+
+# (optional) Configure (comma-separated) tags for control plane and worker machines
+# export CONTROL_PLANE_MACHINE_TAGS="control-plane,controller"
+# export WORKER_MACHINE_TAGS="worker,compute"
+```
 
+You are now all set to deploy the MAAS CAPI infrastructure provider.
 ````
 `````