Commentary fixes related to AEST/AEDT etc.

* antarctica (Antarctica/Casey): Spell out AWST in comment.
* tz-link.htm: Use CST instead of EST in the example, as in Theory, to
match the current database.
* zic.8: Update Australia/Adelaide Zone line example to match current
usage.
A few more commentary fixes related to AEST/AEDT etc.

* antarctica: Shrink commentary to fit into 80 columns.
* tz-link.htm: Rework example to use "CST" throughout.