Update tutorial

docs/Tutorial.md

@@ -88,4 +88,49 @@ graph TD;
   
   classDef impl fill: #4a5659, stroke: #fff, stroke-width: 4px;
   class ArraySeq,MutableArray,MutableArrayList,MutableArrayDeque,MutableSmartArrayList,MutableLinkedList,MutableSinglyLinkedList,MutableEnumSet,MutableHashSet,MutableTreeSet impl;
-```
+```
+
+### Creating collections using factory methods
+
+Most collection interfaces and implementation classes provide a series of convenient static factory methods
+for creating collections.
+
+```java
+// Create a collection from values
+var _ = Seq.of(1, 2, 3); // ==> [1, 2, 3]
+
+// Create a collection from array
+var _ = Seq.from(new Integer[] {1, 2, 3});  // ==> [1, 2, 3]
+
+// Create a collection from any iterable object
+var _ = Seq.from(java.util.List.of(1, 2, 3));  // ==> [1, 2, 3]
+
+// Create a collection from an iterator
+var _ = Seq.from(java.util.List.of(1, 2, 3).iterator());  // ==> [1, 2, 3]
+
+// Create a collection from a stream
+var _ = Seq.from(java.util.stream.Stream.of(1, 2, 3));  // ==> [1, 2, 3]
+
+// Create a seq filled with N identical values
+var _ = Seq.fill(3, "value"); // ===> ["value", "value", "value"]
+
+// Create a seq of N values, each of which is generated by a user-supplied function
+var _ = Seq.fill(3, i -> i + 10); // ===> [10, 11, 12]
+
+// Wrap an existing java.util.List as a Seq (without copying)
+var _ = Seq.wrapJava(List.of(1, 2, 3)); // ===> [1, 2, 3]
+```
+
+In addition, each collection class/interface provides a static `factory()` method 
+to get a `CollectionFactory` corresponding to a collection.
+The `CollectionFactory` instance also provides factory methods similar to the above and can be used as a `java.util.stream.Collector`.
+
+```java
+var _ = Seq.<Integer>factory().of(1, 2, 3); // ===> [1, 2, 3]
+
+// Use as Collector
+var _ = Stream.of(1, 2, 3).collect(Seq.factory()); // ===> [1, 2, 3]
+```
+
+More usage of `CollectionFactory` will be introduced in later chapters.
+