feat(cli): add docgen cmd for mkdocs pages

docs/cli/stack.md

@@ -0,0 +1,16 @@
+# stack
+
+```
+Stack the focused window in the specified direction
+
+Usage: stack <OPERATION_DIRECTION>
+
+Arguments:
+  <OPERATION_DIRECTION>
+          [possible values: left, right, up, down]
+
+Options:
+  -h, --help
+          Print help
+
+```