SQL: [Docs] Add limitation for sorting on aggs (#52210)
SQL: [Docs] Add limitation for sorting on aggs (#52210)

Add a section to point out that when ordering by an aggregate
only plain aggregate functions are allowed, no scalars/operators
can be used on top of them.

Fixes: #52204
gingerwizard/elasticsearch,nknize/elasticsearch,GlenRSmith/elasticsearch,robin13/elasticsearch,HonzaKral/elasticsearch,robin13/elasticsearch,GlenRSmith/elasticsearch,HonzaKral/elasticsearch,gingerwizard/elasticsearch,robin13/elasticsearch,uschindler/elasticsearch,scorpionvicky/elasticsearch,uschindler/elasticsearch,HonzaKral/elasticsearch,gingerwizard/elasticsearch,robin13/elasticsearch,uschindler/elasticsearch,gingerwizard/elasticsearch,GlenRSmith/elasticsearch,gingerwizard/elasticsearch,scorpionvicky/elasticsearch,nknize/elasticsearch,uschindler/elasticsearch,nknize/elasticsearch,nknize/elasticsearch,uschindler/elasticsearch,gingerwizard/elasticsearch,GlenRSmith/elasticsearch,robin13/elasticsearch,scorpionvicky/elasticsearch,scorpionvicky/elasticsearch,HonzaKral/elasticsearch,GlenRSmith/elasticsearch,scorpionvicky/elasticsearch,gingerwizard/elasticsearch,nknize/elasticsearch