[options] Upper-case options and URL in --help output

Hopefully, this reduces confusion as in #4610.

youtube_dl/options.py

@@ -109,7 +109,7 @@ def parseOpts(overrideArguments=None):
     kw = {
         'version': __version__,
         'formatter': fmt,
-        'usage': '%prog [options] url [url...]',
+        'usage': '%prog [OPTIONS] URL [URL...]',
         'conflict_handler': 'resolve',
     }