Update the Foreign key limitations section with indexed vcols

Page: https://mariadb.com/kb/en/foreign-keys/

Indexed generated columns are not supported as innodb foreign key index, both VIRTUAL, or STORED:

create table parent(id int) engine = innodb;

create table child(id int, val int as (id), key(val), foreign key (val) references parent(id)) engine = innodb;

This should work so for both child and parent-side vcols.