docs(angular.merge): add notes about support and lodash compatibility

Closes angular#16187
Closes angular#14512

Author: Narretz

src/Angular.js

@@ -396,8 +396,8 @@ function extend(dst) {
 * sinceVersion="1.6.5"
 * This function is deprecated, but will not be removed in the 1.x lifecycle.
 * There are edge cases (see {@link angular.merge#known-issues known issues}) that are not
-* supported by this function. We suggest
-* using [lodash's merge()](https://lodash.com/docs/4.17.4#merge) instead.
+* supported by this function. We suggest using another, similar library for all-purpose merging,
+* such as [lodash's merge()](https://lodash.com/docs/4.17.4#merge).
 *
 * @knownIssue
 * This is a list of (known) object types that are not handled correctly by this function:
@@ -406,6 +406,8 @@ function extend(dst) {
 * - [`CanvasGradient`](https://developer.mozilla.org/docs/Web/API/CanvasGradient)
 * - AngularJS {@link $rootScope.Scope scopes};
 *
+* `angular.merge` also does not support merging objects with circular references.
+*
 * @param {Object} dst Destination object.
 * @param {...Object} src Source object(s).
 * @returns {Object} Reference to `dst`.
@@ -806,8 +808,10 @@ function arrayRemove(array, value) {
  * </div>
  *
  * @knownIssue
- * This is a non-exhaustive list of object types / features that are not handled correctly by this
- * function:
+ * This is a non-exhaustive list of object types / features that are not handled correctly by
+ * `angular.copy`. Note that since this functions is used by the change detection code, this
+ * means binding or watching objects of these types (or that include these types) might not work
+ * correctly.
  * - [`ImageData`](https://developer.mozilla.org/docs/Web/API/File)
  * - [`Map`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Map)
  * - [`ImageData`](https://developer.mozilla.org/docs/Web/API/ImageData)

src/ngParseExt/module.js

@@ -9,8 +9,8 @@
  *
  * @knownIssue
  * You cannot use Unicode characters for variable names in the {@link ngRepeat} or {@link ngOptions}
- * expressions (e.g. `ng-repeat="f in поля"`), because they don't use the {@link `$parse`} service
- * to parse the expression.
+ * expressions (e.g. `ng-repeat="f in поля"`), because even with `ngParseExt` included, these
+ * special expressions are not parsed by the {@link `$parse`} service.
  *
  * @description
  *