[Feature] Man Page Search Completion

[nicoandmee]

I don't know about you guys, but I frequently refer to man pages in my day-to-day. Sometimes, I may be in the browser and would like to see a pretty and simplified man page for the command in question. Enter MANKIER, a lovely service that aggregates man pages and enhances them with so-called tldr docsets.

As an example, consider the entry for fd, an alternative to the generic find on UNIX systems. It would be great to have search completion and search capabilities for MANKIER in vimium. That's why I've created a PR that adds that support, and starts the process of refactoring MV2 code for MV3 (really, just using Fetch instead of XMLHttpRequest - as it is not available in SW context).

If you also find this feature addition useful please indicate your interest by commenting or upvoting this issue, to bring it to the attention of project maintainers. ❤️