Add link to hosted plugin documentation on ParserError

[anders-kiaer]

When plugins are missing a required argument, or it is of the wrong type, the user is currently provided by a decent error message. Example:

Traceback (most recent call last):
[...]
webviz_config._config_parser.ParserError: The plugin `DataTable` requires the argument `csv_file` in your configuration file.

This could perhaps be further improved by also giving a URL to hosted plugin documentation (if available from the setup.py install script and project_urls["Documentation"]).

[anders-kiaer]

This issue can now probably be closed if we simply add + encourage the user to run webviz docs in the error message.