doc/example.conf.in: Clarify comment for `auto-trust-anchor-file`
doc/example.conf.in: Clarify comment for `auto-trust-anchor-file`

Remove `And enable:` as it refers to the uncommented option.

Fixes: 01dd4a35 ("- Added explicit note on unbound-anchor usage:")

NLnetLabs/unbound,NLnetLabs/unbound,NLnetLabs/unbound,NLnetLabs/unbound