SSL/TLS instead of SSL in docs

In the NSS thread it was discussed (20210603210642.GF22012@momjian.us etc) that
we use SSL rather than TLS in the documentation, which is technically somewhat
incorrect.  Consensus came to using SSL/TLS instead for referring to encrypted
connections.  Since this isn't really limited to the NSS work, I'm breaking
this out into a new thread.

Looking at the docs it turns out that we have a mix of SSL (with one ssl),
SSL/TLS and TLS for referring to the same thing.  The attached changes the
documentation to consistently use SSL/TLS when referring to an encrypted
connection using a TLS protocol, leaving bare SSL and TLS only for referring to
the actual protocols.  I *think* I found all instances, there are many so I
might have missed some, but this version seemed like a good place to continue
the discussion from the previous thread.

Admittedly it gets pretty unwieldy with the <acronym /> markup on SSL and TLS
but I opted for being consistent, since I don't know of any rules for when it
can/should be omitted (and it seems quite arbitrary right now).  Mentions in
titles were previously not marked up so I've left those as is.  I've also left
line breaks as an excercise for later to make the diff more readable.

While in there I added IMO missing items to the glossary and acronyms sections
as well as fixed up markup around OpenSSL.

This only deals with docs, but if this is deemed interesting then userfacing
messages in the code should use SSL/TLS as well of course.

Thoughts?

--
Daniel Gustafsson		https://vmware.com/