Correcting and adjusting Nginx docs (#1098)

* Correcting and adjusting Nginx docs

* Correcting http2 switch, re-adding explicit XSS disable.

* Emphasizing HTTPS config, discouraging HTTP

* Making lint happy

* Missed semicolon

* Removing # to make lint happy

* Make lint happy, yet again

* Correcting subpath documentation for sockets

* Rearragning subpath exmaples to emphasize HTTPS

* Minor syntax change

* Minor syntax change, accidentally removed caution close

* Adding, adjust headers for consistency

* Adding, adjust headers

* add_headers in subpaths, toning down cautions, updating CSP

* minor changes for uniformity

* Adjusting http2 syntax for versions 1.25+

* Adding HTTP3/QUIC options

* Removing QUIC/HTTP3, not ready

* Switching example.org for DOMAIN.TLD for consistency

* Making suggested changes

* minor grammatical changes