docs(argo-workflows): add an HA section (#2183)

* feat(argo-workflows): add a sample HA config

- a `values-ha.yaml` as an example for how one would set-up HA according to the Argo Workflows docs

Signed-off-by: Anton Gilgur <agilgur5@gmail.com>

* docs(argo-workflows): add an HA section

- plus add a test for HA, which the docs link to as an example
- link back to [upstream docs](https://argoproj.github.io/argo-workflows/high-availability/) as well

- follow the same basic structure as the [Argo CD chart for HA](3e35b0c7f7/charts/argo-cd/README.md (L17))
  - as asked in review

Signed-off-by: Anton Gilgur <agilgur5@gmail.com>

---------

Signed-off-by: Anton Gilgur <agilgur5@gmail.com>
Signed-off-by: Anton Gilgur <4970083+agilgur5@users.noreply.github.com>
Co-authored-by: Aikawa <yu.croco@gmail.com>

charts/argo-workflows/ci/ha-values.yaml

@@ -0,0 +1,23 @@
+# Sample values for High Availability configuration, following https://argoproj.github.io/argo-workflows/high-availability/
+
+controller:
+  # in v3.0+, a second controller can be ran as a hot-standby: https://argoproj.github.io/argo-workflows/high-availability/#workflow-controller
+  replicas: 2 # should be strictly greater than PDB minAvailable
+  # enable PDB with at least one Pod
+  pdb:
+    # -- Configure [Pod Disruption Budget] for the controller pods
+    enabled: true
+    minAvailable: 1
+
+server:
+  # enable HPA with at least two Pods
+  autoscaling:
+    # -- Enable Horizontal Pod Autoscaler ([HPA]) for the Argo Server
+    enabled: true
+    # -- Minimum number of replicas for the Argo Server [HPA]
+    minReplicas: 2 # should be strictly greater than PDB minAvailable
+  # enable PDB with at least one Pod
+  pdb:
+    # -- Configure [Pod Disruption Budget] for the controller pods
+    enabled: true
+    minAvailable: 1