Reorder and reword small portions of the keylength documentation and
make the ECC cert default explicitly stated in part 2 to avoid
confusion.
Fixes#6590
Add support for deploying to the Zyxel GS1900 line of switches as long
as those switches are running at least firmware V2.80.
Tested on a Zyxel GS1900-8 and GS1900-24E
Resolves#5042