doc: massive refactor and simplification to migrate to mkdocs

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

doc/config/service-wrappers.md

@@ -0,0 +1,31 @@
+Service Wrapper Scripts
+=======================
+
+If your service requires to run additional commands, executed before the
+service is actually started, like the systemd `ExecStartPre`, you can
+use a wrapper shell script to start your service.
+
+The Finit service `.conf` file can be put into `/etc/finit.d/available`,
+so you can control the service using `initctl`.  Then use the path to
+the wrapper script in the Finit `.conf` service stanza.  The following
+example employs a wrapper script in `/etc/start.d`.
+
+**Example:**
+
+* `/etc/finit.d/available/program.conf`:
+
+        service [235] <!> /etc/start.d/program -- Example Program
+
+* `/etc/start.d/program:`
+
+        #!/bin/sh
+        # Prepare the command line options
+        OPTIONS="-u $(cat /etc/username)"
+
+        # Execute the program
+        exec /usr/bin/program $OPTIONS
+
+> [!NOTE]
+> The example sets `<!>` to denote that it doesn't support `SIGHUP`.
+> That way Finit will stop/start the service instead of sending SIGHUP
+> at restart/reload events.