Revert "scripts/gdb: add documentation example for radix tree"

This reverts commit 9b5580359a84 ("scripts/gdb: add documentation
example for radix tree")

The python implementation of radix tree was merged at the same time as a
refactoring of the radix tree implementation and doesn't work. The
feature is being reverted, thus we revert the documentation as well.

Signed-off-by: Kieran Bingham <kieran@bingham.xyz>