Instead of adding hoops to the documentation, in particular to keep it
in sync, improve the only location where we emit HTC status logs.

We could also consider replacing the HTC enum with a struct, similar to
what we did in other places. The struct symbols would be named after the
UPPER name from the table, have a name and description fields, possibly
replace the error number with a simple is_err field.

Capturing the long description like this is less intrusive.

Refs #4042