cmake: extended zephyr_library_amend description with an extra example

Add some more example to the description of zephyr_library_amend().
This should help users to get input of the extra possibilities that this
function provides.

See: #35770

Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>
Signed-off-by: Andrzej Głąbek <andrzej.glabek@nordicsemi.no>
1 file changed