Revise documentation hovering

[jeapostrophe]

Right now, you're doing a manual process to get the documentation. However, we could modify the Reach documentation generator (https://github.com/reach-sh/reach-lang/tree/539a63081329e64638fc8776eeef2b2a26c993f7/docs-src) to (a) generate a Markdown version and (b) provide a cross-reference file with all of the tokens with corresponding links to the documentation. I'm not sure what the constraints of VSCode are, but I'd love to help you make it better.

[ericglau]

The doc for the supported Markdown format is here. Having tokens to map to the corresponding Markdown text in an automated way would be great.

It would also be good to have some context for what is treated as a particular token (for example, whether it is an identifier or a step). I would need to consider how this context can be represented programatically though.

[hamirmahal]

I think we should fix the formatting for some of the keywords. Reach.App looks like this:

Other keywords' hover descriptions look fine. Particpant's hover text is fine, for instance.