doc/fiasco: Update info

doc/fiasco

@@ -1,11 +1,19 @@
  Copyright (C) 2007-2011  pancake <pancake@youterm.com>
  Copyright (C) 2011-2012  Pali Rohár <pali.rohar@gmail.com>
 
-SPECS FOR TEH FIASCO FIRMWARE FILE FORMAT ffff!
+SPECS FOR THE FIASCO FIRMWARE FILE FORMAT ffff!
 -----------------------------------------------
 
-  These notes has not been taken properly and may be wrong. It must
-  be revised to fit the reality. But this is mostly a general idea:
+  This is final working version of FIASCO format. FIASCO image which
+  is generated by this spec is acceptable by Nokia flasher-3.5 and
+  unpack data same as FIASO image generated by Nokia fiasco-gen. This
+  format is implemented in 0xFFFF and every image which I tested
+  (generated by 0xFFFF and fiasco-gen) was properly unpacked under
+  0xFFFF and flasher-3.5 with same result. Small difference is that
+  fiasco-gen add some unknown subsection block to image header
+  (type '4' or '/') which contains some messy characters... But if
+  these sections missing, flasher-3.5 working fine too. And old FIASCO
+  images (for N8x0) does not have these subsectin...
 
 
 FILE HEADER
@@ -45,5 +53,5 @@ IMAGE
    1 byte           --  length of subsection block
    N bytes          --  subsection block data
              }
-   1 byte           --  unknown (maybe end of subsections?)
+   1 byte           --  unknown (0x00 is accepted, maybe end of subsections?)
    N bytes          --  image data