Introduce `---@doctag`

[numToStr]

          That seems really neat. I did not know you could use `---@brief` twice! Rather, I did not try using it that way. As, for the first line thing, I think a doctag with two parameters would be great, like `---@headmod <tag-name> <version> <lastmod>` to `---@headmod comment-nvim.txt 0.7 2021-07-11`. And, if you do want to support spaces.. I think enclosing them around `""` would be great.

Also, my issues have been solved! This can be closed if you want.

Originally posted by @dharmx in #76 (comment)