* [docs] Add a certificates guide in Advanced
This adds some documentation about the process of getting certificates
through ACME in general. It also provides a number of links to
alternative clients and certbot deployment guides that are up to date.
Slightly restructure the NGINX and Apache reverse proxy documentation
and insert mentions to the Provisioning TLS certificates advanced
documentation in them.
* [docs] Add firewall section in Advanced
* [docs] Add new guides to section indexes
* [docs] Fix spelling issue
* [docs] Fix a few typos
* [docs] Made Advanced its own section
This splits the Advanced page off from the Getting Started guide and
makes it its own thing. It now has some additional sub-sections for
bigger topics like caching and enhanced security. This also moves
tracing from Getting Started to Advanced as that feels like a more
appropriate location for it.
The enhanced security looks a little silly with a single section, but I
have guides pending for firewall configurations and I'd also like to
consolidate our how to provision TLS certificates in there as we repeat
this information multiple times.
* [docs] Fix all my spelling errors
* [docs] Inline the links in sandboxing
