Update and reorganize documentation

- Convert "Common Tasks" to "How-to Guides"
  (QubesOS/qubes-issues#6694)
- Make title capitalization consistent across docs
- Fix leftover h1 headings
- Reorganize various pages and topics
- Update permalinks to better match titles
- Create redirects for changed permalinks
- Miscellaneous cleanup

QubesOS/qubes-issues#6701

user/reference/qubes-service.md

@@ -1,25 +0,0 @@
----
-lang: en
-layout: doc
-permalink: /doc/qubes-service/
-redirect_from:
-- /en/doc/qubes-service/
-- /doc/QubesService/
-- /wiki/QubesService/
-ref: 138
-title: Qubes Service
----
-
-Usage documentation is in the `qvm-service` man page. There are also described predefined services.
-
-Under the hood, an enabled service in a VM is signaled by a file in `/var/run/qubes-service`.
-This can be used to implement an almost enable/disable **per-VM** switch controlled by dom0.
-
-Adding support for systemd services is pretty simple. In the VM, create the following file (and directory, if needed): `/etc/systemd/system/<service name>.service.d/30_qubes.conf`. It should contain the following:
-
-~~~
-[Unit]
-ConditionPathExists=/var/run/qubes-service/<service name>
-~~~
-
-This will cause the service to be started only when you enable it with `qvm-service` for this VM.

user/reference/research.md

@@ -1,15 +0,0 @@
----
-lang: en
-layout: default
-permalink: /research/
-redirect_from:
-- /doc/qubes-research/
-- /en/doc/qubes-research/
-- /doc/QubesResearch/
-- /wiki/QubesResearch/
-ref: 139
-title: Research
----
-
-Here are links to various research papers, projects, and blog posts that relate
-to Qubes OS.

user/reference/tools.md

@@ -10,7 +10,7 @@ redirect_from:
 - /doc/tools/3.2/dom0/
 - /doc/tools/3.2/domU/
 ref: 141
-title: Command-Line Tools
+title: Command-line Tools
 ---