Update help.txt

The args= prefix is no longer needed in the examples. Update the examples to reflect this change.

Add descriptions for the new arguments json / j and gpt / g that are listed in the README.md.

Correct the weird spacing in lines 21-25.

Provide more examples to help users understand how to use the new arguments and the updated format

help.txt

@@ -1,7 +1,7 @@
 Usage:
 
     $ curl localhost:8000                     # current location
-    $ curl localhost:8000?loc=new_york        # surf report in new_york
+    $ curl localhost:8000?loc=new_york        # surf report in New York
 
 Supported location types: