Docs: explain what 'flasher-3.5' means

Explicitly document the need to install a flasher tool and point to the
download sites. 'flasher-3.5' isn't a well known command, and with the
demise of the official distribution sites, it's become hard to find.

Also describe how to do the same thing with 0xFFFF, the free software
replacement for maemo_flasher.

documentation.txt

@@ -49,7 +49,7 @@ anyway, correct?
 
 -and more...
 
-Booting the initrd
+Booting RescueOS
 ~~~~~~~~~~~~~~~
 Note: You can not store persistent data in / as everything happens in RAM. Of
 course, it becomes possible when you mount the EMMC or sd card on the
@@ -58,10 +58,40 @@ corresponding mountpoint.
 Note: It comes without any promises and without any warranty. Therefore you
 are doing everything at your own risk. 
 
-flasher-3.5 -k 2.6.37 -n initrd.img -l -b"rootdelay root=/dev/ram0"
+To load RescueOS onto an N900, you'll need a USB data cable, a PC, and one of
+the following flashers:
 
-wait for "suitable device not found..." and connect the N900 to your 
-Linux box through USB.
+- 0xFFFF - the Open Free Fiasco Firmware Flasher
+  Free/open source, but only runs on GNU/Linux.
+  Packaged for Ubuntu and Debian as '0xffff':
+    http://packages.ubuntu.com/source/0xffff
+    https://packages.debian.org/sid/0xffff
+  Discussion:  http://talk.maemo.org/showthread.php?t=87996
+  Source repo: https://github.com/pali/0xFFFF
+
+- maemo_flasher v3.5 - the original proprietary flasher from Nokia
+  Windows, MacOS, GNU/Linux
+  Official distribution site is gone.  Archive copies at:
+    https://web.archive.org/web/20131117084237/http://skeiron.org/tablets-dev/maemo_dev_env_downloads/
+  Documentation:
+    http://wiki.maemo.org/Documentation/Maemo_5_Developer_Guide/Development_Environment/Maemo_Flasher-3.5
+
+Switch the N900 completely off.  If it is plugged into a charger, a PC, or
+anything else by its USB port, unplug it and wait about 10 seconds to give the
+charger software time to shut down.  Don't connect it to the PC just yet.
+
+Startup the flasher and get it ready to load RescueOS.  For 0xFFFF, the
+incantation is:
+
+  0xFFFF -m kernel:zImage -m initfs:rootfs.cramfs -l -b 'rootdelay root=/dev/ram0'
+
+For maemo_flasher, it's:
+
+  flasher-3.5 -k zImage -n rootfs.cramfs -l -b"rootdelay root=/dev/ram0"
+
+You'll get a message like "suitable device not found...", but the flasher
+should block and wait.  Now connect the N900 to the PC with the data cable; the
+flasher should detect the device, upload RescueOS, launch it, and then exit.
 
 
 ~~~~~~~~~~~~~~~