tcl: fix broken Raspberry Pi website links

tcl: fix broken Raspberry Pi website links

raspberrypi.com is the home for technical information, raspberrypi.org
is the Foundation's site (though there are intelligent redirects).

Several pages have moved around, fix these.

Also tweak a few comments for style and correctness.

Signed-off-by: Jonathan Bell <jonathan@raspberrypi.com>
Change-Id: I7f52bcc362fb213b50987e3a42866fe4a6fec883
Reviewed-on: https://review.openocd.org/c/openocd/+/8885
Tested-by: jenkins
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>