bcm27xx: config: update documentation links

The documentation links have changed and are no longer valid.

Signed-off-by: Álvaro Fernández Rojas <[email protected]>

target/linux/bcm27xx/image/config.txt

@@ -4,7 +4,7 @@
 
 ################################################################################
 # For overclocking and various other settings, see:
-# https://www.raspberrypi.org/documentation/configuration/config-txt/README.md
+# https://www.raspberrypi.com/documentation/computers/config_txt.html
 ################################################################################
 
 # OpenWrt config

target/linux/bcm27xx/image/distroconfig.txt

@@ -5,7 +5,7 @@
 # Restore PL011 (ttyAMA0) to GPIOs 14 & 15, instead of Mini UART (ttyS0).
 # Mini UART is disabled by default unless "enable_uart=1" is specified,
 #  which changes the core frequency to a fixed value and impacts performance.
-# See https://www.raspberrypi.org/documentation/configuration/uart.md
+# See https://www.raspberrypi.com/documentation/computers/configuration.html#mini-uart-and-cpu-core-frequency
 [pi0w]
 dtoverlay=disable-bt
 [pi3]