StackStorm HA `helm install` instructions

[mamercad]

Based on the StackStorm instructions, installation by way of Helm is invoked by helm install stackstorm/stackstorm-ha, which yields:

❯ helm install stackstorm/stackstorm-ha
Error: INSTALLATION FAILED: must either provide a name or specify --generate-name

Based on Helm usage, we need to either:

❯ helm install <name> stackstorm/stackstorm-ha

to specify a <name> for the deployment, or:

❯ helm install --generate-name stackstorm/stackstorm-ha

to have Helm automatically generate a name for the deployment.