doc: massive refactor and simplification to migrate to mkdocs

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

doc/config/task-and-run.md

@@ -0,0 +1,46 @@
+run (sequence)
+--------------
+
+**Syntax:** `run [LVLS] <COND> /path/to/cmd ARGS -- Optional description`
+
+> `<COND>` is described in the [Services](services.md) section.
+
+One-shot command to run in sequence when entering a runlevel, with
+optional arguments and description.  `run` commands are guaranteed to be
+completed before running the next command.  Useful when serialization is
+required.
+
+> [!WARNING]
+> Try to avoid the `run` command.  It blocks much of the functionality
+> in Finit, like (re)starting other (perhaps crashing) services while a
+> `run` task is executing.  Use other synchronization mechanisms
+> instead, like conditions.
+
+Incomplete list of unsupported `initctl` commands in `run` tasks:
+
+ - `initctl runlevel N`, setting runlevel
+ - `initctl reboot`
+ - `initctl halt`
+ - `initctl poweroff`
+ - `initctl suspend`
+
+To prevent `initctl` from calling Finit when enabling and disabling
+services from inside a `run` task, use the `--force` option.  See
+also the `--quiet` and `--batch` options.
+
+task (parallel)
+---------------
+
+**Syntax:** `task [LVLS] <COND> /path/to/cmd ARGS -- Optional description`
+
+> `<COND>` is described in the [Services](services.md) section.
+
+One-shot like 'run', but starts in parallel with the next command.
+  
+Both `run` and `task` commands are run in a shell, so basic pipes and
+redirects can be used:
+
+    task [s] echo "foo" | cat >/tmp/bar
+
+Please note, `;`, `&&`, `||`, and similar are *not supported*.  Any
+non-trivial constructs are better placed in a separate shell script.