I don't think it's worth the effort writing another section on regex, just link to https://regex101.com/ https://regex101.com/ or http://www.regexr.com/ http://

I don't think it's worth the effort writing another section on regex, just link to https://regex101.com/ https://regex101.com/ or http://www.regexr.com/ http://www.regexr.com/ a cheatsheet and call it done.