Add tooltip to attribute type

[amomchilov]

1. Move the [R] part outside the underlined and linked <a> tag

2. Add a title field to explain what [R], [W] or [RW] mean.

   It's fairly self-explanatory if you see [RW], but on many APIs' docs, you'll only have a bunch of [R]s, so you'll be missing that context clue.

   On hover, it shows one of:

   • attr_reader
   • attr_writer
   • attr_accessor

Before	After

[matzbot]

🚀 Preview deployment available at: https://7eff1332.rdoc-6cd.pages.dev (commit: 1468aea)

[michaelherold]

The behavior of the ¶ is quite confusing with this change. It pops up when you hover over anything in the div, but appears to be associated with the a. I'm not really sure what its purpose is as there is no click/select behavior attached to it. My guess is that it's there to make hovering the link more obvious.

I like the change, but think we should address the pilcrow's (TIL its name) behavior as part of it.