NEWS: updates for v0.3.1
NEWS: updates for v0.3.1

Add release notes for libgpiod v0.3.1.

Signed-off-by: Bartosz Golaszewski <108de5fbc428215dc26df4468b48691526611148@gmail.com>

brgl/libgpiod,brgl/libgpiod,brgl/libgpiod,brgl/libgpiod