Add more notes to messages

[wooorm]

Subject of the issue

alex has a nice little feature, on the command line, so that it shows a bit more information on why it tells you about stuff, if you run alex like so: alex --why some-file.md

An example of how this works can be seen for the pattern that suggests alternatives for hearing impaired

We don’t have a lot of those though, and could use some more notes on terms!

[annakau]

I could try to add some notes

[agans]

Hi, I opened a PR to help contribute to this issue, if anyone would like to take a look - thanks! https://github.com/retextjs/retext-equality/pull/51