Two new documentation pages: "How Logging Works" and "Architecture"

Along with a new aesthetically-pleasing design (clear your browser cache!), I added two more pages to the documentation in response to a lot of questions and confusion over the past couple weeks:

The article about logging should make it pretty clear how logging works in Caddy 2, and why it’s probably different from what you’re used to in old-school web servers.

The architecture page gives a high-level explanation about how Caddy works as a piece of software. It explains what modules are and how the config structure is managed.

I hope these are helpful!