[r] clean up svds docs

[immanuelazn]

I've noticed that the math doesn't get rendered correctly in Details. Looks like a copy-pasta from RSpectra, but \eqn blocks in \describe{\item{}} don't render correctly in our book. I did a minimal fix by converting the offending lines into code lines instead.

See the offending reference here.

Also fixed numbers and variables to be repesented as code blocks across params.

[bnprks]

Nice initiative on putting in a suggested fix, but I think the equation rendering is fixed already by a pending change that's currently in PR 189, as described in my comment on PR 168. It appears the pkgdown bug has a fix that was merged about a week ago, but it'll still be some time before it gets into a CRAN release I think.

It took me a while to re-figure out what was going on, because in the current main branch with a latest pkgdown installed it's impossible to get any equation to render correctly. I think with the fix I linked applied all of the equations render just fine (though some of your other changes like getting rid of the duplicate parameter comment seem good still).

Also, I think for things that are mostly fixing typos in docs/error messages/warning messages I think it's okay not to list as a separate item in the NEWS file

[immanuelazn]

Cool, thanks! I forgot about that change, was mainly concerned about how the \eqn blocks that were working in my #189 weren't working when copy pasted into this branch's lists. But probably should have done a due diligence check in params too.

In any case, I'll remove those changes and just keep the docs styling changes for the non equation blocks.