doc: put all the u-boot/serial stuff in one place to link from

devices/gl-mt300a/default.nix

@@ -1,6 +1,6 @@
 # GL.iNet GL-MT300A
 
-rec {
+{
   system = {
     crossSystem = {
       config = "mipsel-unknown-linux-musl";
@@ -13,34 +13,11 @@ rec {
 
   description = ''
     GL.iNet GL-MT300A
-    ********************
+    *****************
 
     The GL-MT300A is based on a MT7620 chipset.
 
-    The GL.iNet pocket router range makes nice cheap hardware for
-    playing with Liminix or similar projects. The manufacturers seem
-    open to the DIY market, and the devices have a reasonable amount
-    of RAM and are much easier to get serial connections than many
-    COTS routers.
-
-    Wire up the serial connection: this probably involves opening
-    the box, locating the serial header pins (TX, RX and GND) and
-    connecting a USB TTL converter - e.g. a PL2303 based device - to
-    it. The defunct OpenWRT wiki has a guide with some pictures. (If
-    you don't have a USB TTL converter to hand, other options are
-    available. For example, use the GPIO pins on a Raspberry Pi.)
-
-    Run a terminal emulator such as Minicom on whatever is on the
-    other end of the link. I use 115200 8N1 and find it also helps
-    to set "Line tx delay" to 1ms, "backspace sends DEL" and
-    "lineWrap on".
-
-    When you turn the router on you should be greeted with some
-    messages from U-Boot and a little bit of ASCII art, followed by
-    the instruction to hit SPACE to stop autoboot. Do this and you
-    will get a gl-mt300a> prompt.
-
-    For flashing from uboot, the firmware partition is from
+    For flashing from U-Boot, the firmware partition is from
     0xbc050000 to 0xbcfd0000.
 
     WiFi on this device is provided by the rt2800soc module. It
@@ -54,7 +31,6 @@ rec {
     OpenWrt web page: https://openwrt.org/toh/gl.inet/gl-mt300a
 
   '';
-  installer = "flashimage";
 
   module = { pkgs, config, lib, ...}:
     let
@@ -67,7 +43,7 @@ rec {
     in {
       imports = [ ../../modules/arch/mipsel.nix ];
       hardware = {
-        defaultOutput = installer;
+        defaultOutput = "flashimage";
         loadAddress = "0x80000000";
         entryPoint  = "0x80000000";