README: Add requirements section

- New requirements section about what Finit expects from the system
- Remove commented out `udevadm settle` code, now in README

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

README.md

@@ -326,6 +326,32 @@ Dropbear SSH service will not be restarted if it is killed or exits.
     6:2       inetd  0       [345]      /sbin/dropbear allow *:22 deny eth0
 
 
+Requirements
+------------
+
+Finit is capable of running on both desktop/server systems with udev and
+embedded systems that usually come with BusyBox mdev.  Finit probes for
+them at runtime and expects `/dev/` to be writable, usually `devtmpfs`.
+It is also possible to run on a statically set up `/dev` if needed.  It
+is however not a good idea to have both udev and mdev installed at the
+same time, this will lead to unpredictable results.
+
+At boot Finit calls either `mdev` or `udevd` to populate `/dev`, this is
+done slightly differently and on systems with udev you might want to add
+the following one-shot task early in your `/etc/finit.conf`:
+
+    run [S] /sbin/udevadm settle --timeout=120 -- Waiting for udev
+
+Finit has a built-in Getty for TTYs, but requires a working `/bin/login`
+or `/bin/sh`, if no TTYs are configured in `/etc/finit.conf`.
+
+For a fully operational system `/var`, `/run` and `/tmp` must be set up
+properly in `/etc/fstab` -- which is iterated over at boot.
+
+The built-in Inetd requires `/etc/services` and `/etc/protocols` to work
+with port names rather than numbers.
+
+
 Running
 -------
 

finit.c

@@ -354,11 +354,6 @@ int main(int argc, char* argv[])
 	if (fexist("/sbin/udevadm")) {
 		run("/sbin/udevadm trigger --action=add --type=subsystems");
 		run("/sbin/udevadm trigger --action=add --type=devices");
-		/*
-		 * Debian also calls `settle` here, but not Archlinux ...
-		 * ... with settle some systems stop working (pulseaudio)
-		 * run("/sbin/udevadm settle --timeout=120");
-		 */
 	}
 
 	/*