docs(readme.md): update the usage docs to use the two subclasses

README.md

@@ -8,18 +8,26 @@ npm i binary-heap.js
 
 # Usage
 ```js
-const binaryHeap = new BinaryHeap(
-    (x) =>x
-)
+const maxHeap = new MaxHeap( (x) =>x );
+maxHeap.insert(3);
+maxHeap.insert(5);
+maxHeap.insert(7);
+
+maxHeap.pop() // 7
+maxHeap.pop() // 5
+maxHeap.pop() // 3
+maxHeap.pop() // undefined
+
+const minHeap = new MinHeap( (x) =>x );
 
-binaryHeap.insert(3);
-binaryHeap.insert(5);
-binaryHeap.insert(7);
+maxHeap.insert(5);
+maxHeap.insert(3);
+maxHeap.insert(7);
 
-binaryHeap.pop() // 7
-binaryHeap.pop() // 5
-binaryHeap.pop() // 3
-binaryHeap.pop() // undefined
+maxHeap.pop() // 3
+maxHeap.pop() // 5
+maxHeap.pop() // 7
+maxHeap.pop() // undefined
 ```
 
 # Constructor
@@ -28,7 +36,6 @@ binaryHeap.pop() // undefined
 | :---        |    :----:   | :---: | :---: |         ---: |
 | extractor      | function |    false |   | function that extracts the key used for sorting elements in the heap (should be equal to identity for primitive data types)   |
 | iterator   | IterableIterator  | false| | Used to provide the heap with initial elements |
-MaxHeap | boolean | false | true | determines the order of the heap (maximum or minimum)
 
 Works with any data structure that implements the iteratable interface to provide it's elements
 ```js
@@ -40,19 +47,19 @@ map.set(1,1)
 map.set(2,2)
 map.set(3,3);
 
-const binaryHeapOne = new BinaryHeap(
+const maxHeapOne = new MaxHeap(
     (x) =>x,
     arr.values(),
     false
 );
 
-const binaryHeapOne = new BinaryHeap(
+const maxHeapTwo = new MaxHeap(
     (x) =>x,
     sets.values(),
     false
 );
 
-const binaryHeapOne = new BinaryHeap(
+const maxHeapThree = new MaxHeap(
     (x) =>x,
     map.keys().values(),
     false
@@ -63,7 +70,7 @@ Works with complex objects as long as you provide the right extractor
 ```js
 const arr = [{id:1},{id:2},{id:3}];
 
-const binaryHeap = new BinaryHeap(
+const maxHeap = new MaxHeap(
     (x) =>x.id,
     arr.values(),
     false