[ci skip] 📝 Fix returns in api doc for model.schema

Closes #4053

lib/model.js

@@ -917,7 +917,7 @@ Model.prototype.dropSchema = function(schema) {
  * @param {Object} [options]
  * @param {String} [options.schemaDelimiter='.'] The character(s) that separates the schema name from the table name
  * @param {Function} [options.logging=false] A function that gets executed while running the query to log the sql.
- * @return this
+ * @return {this}
  */
 Model.prototype.schema = function(schema, options) {
   this.options.schema = schema;