How should we add Regexps' projects to the list?

[RegexHq](https://github.com/regexhq) is a GitHub organization around Regex. They define themself as a centralized place for community-driven collections of RegExp patterns and tools that can make our life easier. You may want to check [/regexps/meta/issues](https://github.com/regexps/meta/).

I wonder if we should add the link directly or just some projects.

@sindresorhus is a collaborator of the project. It may be a nice idea to check with him, but first I will check their projects myself. They are a lot of excellent resource here. He is also the maintener of an [awesome](https://github.com/sindresorhus/awesome/issues/147) list.