(sessions): Add daily_study_cap system.

data/migration/v5-v6/migration.sql

@@ -174,3 +174,5 @@ AS $$
     );
   END;
 $$ LANGUAGE PLPGSQL;
+
+ALTER TABLE guild_config ADD COLUMN daily_study_cap INTEGER;

data/schema.sql

@@ -78,7 +78,7 @@ CREATE TABLE guild_config(
   returning_message TEXT,
   starting_funds INTEGER,
   persist_roles BOOLEAN,
-  max_daily_study INTEGER
+  daily_study_cap INTEGER
 );
 
 CREATE TABLE ignored_members(