added some documentation for include and all function

lib/abstract-class.js

@@ -301,6 +301,7 @@ AbstractClass.find = function find(id, cb) {
  * @param {Object} params (optional)
  *
  * - where: Object `{ key: val, key2: {gt: 'val2'}}`
+ * - include: String, Object or Array. See AbstractClass.include documentation.
  * - order: String
  * - limit: Number
  * - skip: Number
@@ -392,16 +393,32 @@ AbstractClass.count = function (where, cb) {
 };
 
 /**
+ * Allows you to load relations of several objects and optimize numbers of requests.
  *
+ * @param {Array} objects - array of instances
+ * @param {String}, {Object} or {Array} include - which relations you want to load.
+ * @param {Function} cb - Callback called when relations are loaded
+ *
+ * Examples:
+ *
+ * - User.include(users, 'posts', function() {}); will load all users posts with only one additional request.
+ * - User.include(users, ['posts'], function() {}); // same
+ * - User.include(users, ['posts', 'passports'], function() {}); // will load all users posts and passports with two
+ *     additional requests.
+ * - Passport.include(passports, {owner: 'posts'}, function() {}); // will load all passports owner (users), and all
+ *     posts of each owner loaded
+ * - Passport.include(passports, {owner: ['posts', 'passports']}); // ...
+ * - Passport.include(passports, {owner: [{posts: 'images'}, 'passports']}); // ...
  *
- * @param objects
- * @param include
  */
-AbstractClass.include = function (objects, include, callback) {
+AbstractClass.include = function (objects, include, cb) {
     var self = this;
 
-    if ((include.constructor.name == 'Array' && include.length == 0) || (include.constructor.name == 'Object' && Object.keys(include).length == 0)) {
-        callback(null, objects);
+    if (
+        (include.constructor.name == 'Array' && include.length == 0) ||
+        (include.constructor.name == 'Object' && Object.keys(include).length == 0)
+        ) {
+        cb(null, objects);
         return;
     }
 
@@ -412,13 +429,13 @@ AbstractClass.include = function (objects, include, callback) {
 
     var nbCallbacks = 0;
     for (var i = 0; i < include.length; i++) {
-        var cb = processIncludeItem(objects, include[i], keyVals, objsByKeys);
-        if (cb !== null) {
+        var callback = processIncludeItem(objects, include[i], keyVals, objsByKeys);
+        if (callback !== null) {
             nbCallbacks++;
-            cb(function() {
+            callback(function() {
                 nbCallbacks--;
                 if (nbCallbacks == 0) {
-                    callback(null, objects);
+                    cb(null, objects);
                 }
             });
         }