Fix undocumented methods in the List class ( #878) (#883)

Also noted that the ```add``` method returns the added item.

doc/site/modules/core/list.markdown

@@ -22,7 +22,19 @@ Creates a new empty list. Equivalent to `[]`.
 
 ### **add**(item)
 
-Appends `item` to the end of the list.
+Appends `item` to the end of the list. Returns the added item.
+
+### **addAll**(other)
+
+Appends each element of `other` in the same order to the end of the list. `other` must be [an iterable](../../control-flow.html#the-iterator-protocol).
+
+<pre class="snippet">
+var list = [0, 1, 2, 3, 4]
+list.addAll([5, 6])
+System.print(list) //> [0, 1, 2, 3, 4, 5, 6]
+</pre>
+
+Returns the added items.
 
 ### **clear**()
 
@@ -173,3 +185,13 @@ var other = ["d", "e", "f"]
 var combined = letters + other
 System.print(combined)  //> [a, b, c, d, e, f]
 </pre>
+
+### **\***(count) operator
+
+Creates a new list by repeating this one ```count``` times. It is a runtime error if ```count``` is not a non-negative integer.
+
+<pre class="snippet">
+var digits = [1, 2]
+var tripleDigits = digits * 3
+System.print(tripleDigits) //> [1, 2, 1, 2, 1, 2] 
+</pre>