Added help messages to cli commands

src/cpl_cli/command/build_service.py

@@ -18,6 +18,8 @@ class BuildService(CommandABC):
     @property
     def help_message(self) -> str:
         return textwrap.dedent("""\
+        Copies an python app into an output directory named build/ at the given output path. Must be executed within a CPL workspace or project directory
+        usage: cpl build
         """)
 
     def run(self, args: list[str]):