update-schema.txt

-- update schema:

alter table users change column locked_util locked_until bigint not null;

alter table topics add column ref_type varchar(50) not null after board_id;

alter table topics add column ref_id varchar(50) not null after ref_type;

alter table categories add column tag varchar(100) not null after name;

alter table wikis change column tags tag varchar(100) not null;