Website patch request: documentation style update

In the thread at [1], we agreed to adopt a new layout for the
documentation's tables of functions/operators, which will require
a "hanging indent" layout for cells within those tables. So far
as I've found, there's no good way to specify that within the .sgml
files proper. The preferred way to do it seems to be to attach a
"role" attribute to affected <entry> tags, and then key off of that
to apply the appropriate style adjustments in CSS. So I'd like to
request that the website be updated more or less per the attached.

It's likely that I've missed something about how best to do that ---
I'm not even totally sure that main.css is the best place to
put this change. So feel free to adjust as you see fit.

regards, tom lane

[1] https://www.postgresql.org/message-id/flat/8691.1586798003%40sss.pgh.pa.us