Documentation: Fix a few spelling issues

Signed-off-by: Martin Roth <gaumless@gmail.com>
Change-Id: I47add663f3021170b840203ce229acf836b7a1c4
Reviewed-on: https://review.coreboot.org/c/coreboot/+/64749
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Elyes Haouas <ehaouas@noos.fr>
Reviewed-by: Felix Singer <felixsinger@posteo.net>

Documentation/getting_started/architecture.md

@@ -3,7 +3,7 @@
 ## Overview
 ![][architecture]
 
-[architecture]: comparision_coreboot_uefi.svg
+[architecture]: comparison_coreboot_uefi.svg
 
 ## Stages
 coreboot consists of multiple stages that are compiled as separate binaries and

Documentation/mainboard/acer/g43t-am3.md

@@ -134,7 +134,7 @@ SPI_ROM1 header while the board is off and disconnected from power. There
 seems to be a diode that prevents the external programmer from powering the
 whole board.
 
-The signal assigment on the header is identical to the pinout of the flash
+The signal assignment on the header is identical to the pinout of the flash
 chip. The pinout diagram below is valid when the PCI slots are on the left
 and the CPU is on the right. Note that HOLD# and WP# must be pulled high
 (to VCC) to be able to flash the chip.

Documentation/northbridge/intel/sandybridge/nri_registers.md

@@ -1899,7 +1899,7 @@ Please handle with care!
 +===========+==================================================================+
 |        0:7|  PDWN_idle_counter, This defines the rank indle period in DCLK   |
 |           |  cycles that causes power-down entrance. The minimum value       |
-|           |  should be greater then or equal to the worst roundtrip time     |
+|           |  should be greater than or equal to the worst roundtrip time     |
 |           |  plus burst length.                                              |
 +-----------+------------------------------------------------------------------+
 |       8:10|  PDWN_mode, selects the mode of power-down:                      |