docs: fixed CLI args description

There is no -I argument, it's -i instead. Also, documented -w and -e
arguments.

Change-Id: I30f8682f5be3c08b0bce4f7cb0d6659f342b4621

doc/source/man/bashate.rst

@@ -23,7 +23,9 @@ OPTIONS
 
 --help, -h        Print help
 --verbose, -v     Verbose output
---ignore, -I      Tests to ignore, comma separated
+--ignore, -i      Tests to ignore, comma separated
+--error, -e       Tests to trigger errors instead of warnings, comma separated
+--warn, -w        Tests to trigger warnings instead of errors, comma separated
 
 EXAMPLES
 ========