.github: Skip unnecessary docs test
.github: Skip unnecessary docs test

We don't need to run documentation tests if the documentation is
untouched.

Signed-off-by: Paul Chaignon <a027184a55211cd23e3f3094f1fdc728df5e0500@cilium.io>

michi-covalent/cilium,cilium/cilium,michi-covalent/cilium,tklauser/cilium,cilium/cilium,tklauser/cilium,tklauser/cilium,michi-covalent/cilium,cilium/cilium,tklauser/cilium,cilium/cilium,michi-covalent/cilium,michi-covalent/cilium,tklauser/cilium,cilium/cilium