kyaml: refactor command documentation into .md files from go files

No new documentation added.

cmd/config/docs/commands/fmt.md

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+## fmt
+
+Format yaml configuration files.
+
+### Synopsis
+
+Format yaml configuration files.
+
+Fmt will format input by ordering fields and unordered list items in Kubernetes
+objects.  Inputs may be directories, files or stdin, and their contents must
+include both apiVersion and kind fields.
+
+- Stdin inputs are formatted and written to stdout
+- File inputs (args) are formatted and written back to the file
+- Directory inputs (args) are walked, each encountered .yaml and .yml file
+  acts as an input
+
+For inputs which contain multiple yaml documents separated by \n---\n,
+each document will be formatted and written back to the file in the original
+order.
+
+Field ordering roughly follows the ordering defined in the source Kubernetes
+resource definitions (i.e. go structures), falling back on lexicographical
+sorting for unrecognized fields.
+
+Unordered list item ordering is defined for specific Resource types and
+field paths.
+
+- .spec.template.spec.containers (by element name)
+- .webhooks.rules.operations (by element value)
+
+### Examples
+
+	# format file1.yaml and file2.yml
+	kyaml fmt file1.yaml file2.yml
+
+	# format all *.yaml and *.yml recursively traversing directories
+	kyaml fmt my-dir/
+
+	# format kubectl output
+	kubectl get -o yaml deployments | kyaml fmt
+
+	# format kustomize output
+	kustomize build | kyaml fmt