[installer]: document the commands naming convention and usage

Author: Simon Emms

install/installer/cmd/README.md

@@ -0,0 +1,35 @@
+# Cmd
+
+Publicly available commands are part of our user contract. They use [Cobra](https://cobra.dev/) to build the Golang CLI commands.
+
+## Commands
+
+### config
+
+These are designed to manipulate configuration files and generate a configuration file that can be used to install Gitpod.
+
+#### init
+
+> This replaces `init`, which is now deprecated
+
+This should be run first. This will generate a new `gitpod.config.yaml` file with the default values configured.
+
+#### build-from-envvars
+
+This builds the config from environment variables.
+
+#### cluster
+
+Cluster commands are designed to deploy a Kubernetes resource to the cluster and generate the config value based upon the result. Typically (although not exclusively), these will be Jobs.
+
+##### shiftfs
+
+Detects whether ShiftFS is supported on the cluster for building images. If not, this will default to Fuse.
+
+#### files
+
+Files commands are designed to be run against the file structure. They may be run directly on the node, or by mounting the file system as a volume in a pod.
+
+##### containerd
+
+Detects the containerd settings for a cluster. This will return the location of the containerd socket and the path to the directory.