build: Simplify by removing extra documentation

The Meson adapter scripts are simple enough that they don't need
detailed descriptions for their command line arguments.  The cost of
formulating succint descriptions doesn't justify the benefits.

https://github.com/containers/toolbox/pull/1216

completion/meson_generate_completions.py

@@ -23,9 +23,6 @@ import sys
 if len(sys.argv) != 3:
     print('{}: wrong arguments'.format(sys.argv[0]), file=sys.stderr)
     print('Usage: {} [SOURCE DIR] [COMPLETION TYPE]'.format(sys.argv[0]), file=sys.stderr)
-    print()
-    print("SOURCE DIR is path to the Toolbox Go source code")
-    print("COMPLETION TYPE is either 'bash', 'zsh' or 'fish'")
     sys.exit(1)
 
 source_dir = sys.argv[1]