docs(web): capitalize the name of a parser

Author: masatake

docs/optlib.rst

@@ -465,7 +465,7 @@ When defining a new parser specific field, it is disabled by default. Enable the
 field explicitly to use the field. See ":ref:`Parser specific fields <parser-specific-fields>`"
 about ``--fields-<LANG>`` option.
 
-`passwd` parser is a simple example that uses ``--fields-<LANG>`` option.
+`Passwd` parser is a simple example that uses ``--fields-<LANG>`` option.
 
 By default, ctags assumes the field is a part of the language specified
 with `<LANG>` in ``--regex-<LANG>``. Together with ``{_language=<LANG>}``