docs: Integrate with readthedocs.org

This patch adds configuration to integrate with readthedocs.org, using
mkdocs as rendering engine.

It also does minor documentation updates, to tidy some things up
(clearer titles, move some documentation from the root into docs/, etc).

.mkdocs.yml

@@ -0,0 +1,29 @@
+# mkdocs configuration
+#
+# To test changes locally, run:
+#   mkdocs serve -f .mkdocs.yml
+
+site_name: chasquid documentation
+
+# Point the repo to github to make it easier for users to do edits, even if
+# it's not the canonical location.
+repo_url: https://github.com/albertito/chasquid
+
+markdown_extensions:
+  - codehilite:
+      guess_lang: false
+
+theme: readthedocs
+
+nav:
+- Home: index.md
+- How-to: howto.md
+- Install: install.md
+- Manpages: man/index.md
+- All:
+    - hooks.md
+    - dovecot.md
+    - dkim.md
+    - flow.md
+    - monitoring.md
+