doc: Fix network_ops -> inet_ops in SpGiST operator class list
network_ops is an opclass family of SpGiST, and the opclass able to
work on the inet type is named inet_ops.
Oversight in
7a1cd52, that reworked the design of the table listing all
the operators available.
Reported-by: Laurence Parry
Reviewed-by: Tom Lane, David G. Johnston
Discussion: https://postgr.es/m/
167458110639.
2667300.
14741268666497110766@wrigleys.postgresql.org
Backpatch-through: 14