Minor documentation updates

Makefile

@@ -309,6 +309,10 @@ endef
 # define two targets with one define..
 # $1 = FL2 filename basename
 # $2 = ISO image basename
+#
+# TODO - checking the checksum here is probably too strict - it adds
+# more barriers to downloading some random bios ISO and starting to port
+# the code to it.
 define rule_fl2_extract
     $(1).orig: $(2).orig ; ./scripts/copyFL2 from_iso $(2).orig $(1).orig && ./scripts/checksum --rm_on_fail $(2).orig
 endef

scripts/copyFL2

@@ -6,7 +6,9 @@
 # All the bios update iso images I have checked have had a fat16 filesystem
 # embedded in a dos mbr image as the el-torito ISO payload.  They also all
 # had the same offset to this fat filesystem, so hardcode that offset here.
-# TODO - one day, this offset will be wrong.  Deal with that..
+# The offset value is bytes in decimal.
+# TODO - one day, this offset will be wrong.  (geteltorito could be taught
+# to output the starting sector it found as a starting point)
 FAT_OFFSET=71680
 
 DIR="$1"