manual multiboot note update

doc/MANUAL.md

@@ -232,14 +232,16 @@ and "tinyfpgasp" application can be used to write or read arbitrary
 image to FPGA SPI config FLASH.
 
 User bitstream should be uploaded to byte address 0x200000 of SPI config
-FLASH. Bootloader in multiboot mode resides in multiple copies on SPI config
+FLASH at 12/25/45F (I'm not sure for 85F).
+Bootloader in multiboot mode resides in multiple copies on SPI config
 FLASH chip. "primary"
 bootloader image is at byte address 0 of SPI config FLASH, "golden"
 bootloader image is at 0x140000 address on 45F chip but its location
 varies on various sizes of FPGA 12/25/45/85F. At the last 256 bytes of
 FLASH are some special FPGA lattice boot state machine commands
-(like some primitive CPU assemlby) that setups and controls multiboot
-function. Try not to overwrite any of boot realted areas with something
+(detailed meaning and format not yet known, it's like some primitive CPU assemlby)
+that setups and controls multiboot function.
+Try not to overwrite any of boot related areas with something
 else otherwise US1 or JTAG recovery will be required.
 
 # Programming over JTAG header