Deduplicate link anchors in the ARM

Deduplicate link anchors in the ARM

Some statement names like "allow-query" had manually defined link anchor
_allow-query and also implicit anchor created by
.. namedconf:statement:: syntax. This causes warnings if a ambiguous
reference is made using :any:`allow-query` syntax.

Remove (hopefully all) manually defined anchors which pointed to
identical place as the implicit anchor. This allows :any: to work.

In rare cases where manual anchor points to descriptive text separated
from statement definition the reference was disamguated by replacing
:any:`notify` with :ref:`notify` (for manual anchor)
vs. :namedconf:ref:`notify` (for statement definition).

Please note that `options` statement is a trap: It is ambiguous even
without manual anchor because rndc.conf has its own `options`. Use
:namedconf:ref:`options` vs. :rndcconf:ref:`options` to select
appropriate target.