[sequelize] Add explanation for Model.associate? method

types/sequelize/index.d.ts

@@ -4085,6 +4085,15 @@ declare namespace sequelize {
         /**
          * Set associations with other models
          *
+         * Not part of the sequelize API, used as convention to associate models after creation. e.g.:
+         * ```js
+         * Object.keys(models).forEach(modelName => {
+         *   if (models[modelName].associate) {
+         *     models[modelName].associate(models);
+         *   }
+         * });
+         * ```
+         *
          * @param models
          */
         associate?(models: Models): void;

types/sequelize/sequelize-tests.ts

@@ -1523,6 +1523,13 @@ s.define( 'ScopeMe', {
     }
 } );
 
+// Test convention method used to associate models after creation
+Object.keys(s.models).forEach(modelName => {
+    if (s.models[modelName].associate) {
+        s.models[modelName].associate(s.models);
+    }
+});
+
 // Generic find options
 interface ChairAttributes {
     id: number;