Add support for prefix option

[LuigiPulcini]

A new --prefix option will allow limiting the output to hooks matching the prefixes passed as a comma-separated list. For example, --prefix=my_theme,my_plugin would include my_theme_some_hook and my_plugin_some_other_hook but exclude not_my_hook from the output.

This can be useful when developers need to document the proprietary action and filter hooks introduced by their theme or plugin.

[remcotolsma]

Thanks for the pull request @LuigiPulcini, i merged this, but did some changes afterwards. I'm not the biggest regular expression fan, so changed preg_match to str_starts_with. And if you want to check multiple prefixes you have to add more options.

--prefix=my_theme --prefix=my_plugin

https://github.com/pronamic/wp-documentor#--prefixprefix

[LuigiPulcini]

Thanks for merging this into the main branch. I think your changes would work anyway. After all, the main use case for this new option would be returning hooks that start with the provided prefixes.

Thanks again for this great tool.