Problem:
The `:checkhealth` buffer uses the help syntax, so help tag links (e.g.
`|clipboard|`) are highlighted like they are in help buffers. However,
unlike in help buffers, `CTRL-]` doesn't jump to the relevant help file.
I expect that if the `:checkhealth` buffer looks like a help buffer,
then it should behave like one where it makes sense. This comment from
/r/neovim suggests that this was the intention:
https://www.reddit.com/r/neovim/comments/5ghv3r/see_clipboard_how/dascnry/.
Solution:
Set `'tags'` in `checkhealth` buffers so that `:tag` and friends look
for tags in the help tags files.
c4285acb92
