Update README.md.

Fix some texts and add a notation for using example codes.

README.md

@@ -56,19 +56,19 @@ perfect-scrollbar supports optional parameters.
 
 ### wheelSpeed
 The scroll speed applied to mousewheel event.  
-Default: 10
+**Default: 10**
 
 ### wheelPropagation
 If this option is true, when the scroll reach the end of the side, mousewheel event will be propagated to parent element.  
-Default: false
+**Default: false**
 
 ### minScrollbarLength
 When set to an integer value, the thumb part of the scrollbar will not shrink below that number of pixels.  
-Default: null
+**Default: null**
 
 ### useBothWheelAxes
-When set to true, and only one (vertical or horizontal) scrollbar is visible then both vertical and horizontal scrolling will affect the scrollbar.
-Default: false
+When set to true, and only one (vertical or horizontal) scrollbar is visible then both vertical and horizontal scrolling will affect the scrollbar.  
+**Default: false**
 
 How to Use
 ----------
@@ -112,6 +112,8 @@ $("#Demo").scrollTop(0);
 $("#Demo").perfectScrollbar('update');
 ```
 
+Also you can get the informations about how to use the plugin from example codes in the `examples` directory of the source tree.
+
 Very helpful friends
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