It's about time to remove the infamous CAVEATS section in iked(8).

It's about time to remove the infamous CAVEATS section in iked(8).
Software is never "finished" but the implementation has matured enough
to drop the disclaimer about using it in production networks.

Thanks to markus@, mikeb@ and Hans-Joerg Hoexer for their significant
and ongoing work on improving iked(8).

Removal prompted by sthen@ and many others.