Add docs for lock screen plugin

Author: Ian Maffett

docs/plugins/af.lockscreen.md

@@ -0,0 +1,72 @@
+#Lockscreen
+
+The lockscreen enables developers of hybrid apps to present a lock screen to users.
+Users are required to enter a 4 digit pin to unlock it.  This can easily be bypassed
+on web browsers
+
+```
+$(document.body).lockScreen(opts)
+```
+
+## Properties
+
+#### Attributes
+You can object of options
+
+```
+logo                            (string) image to show above password box
+roundKeyboard                    (boolean) When set to true, rounded keys are shown
+
+
+```
+
+#### Functions
+
+```
+renderKeyboard(function)        Function to render the keyboard.  This returns a string
+validatePassword(function)      Function to validate the password.  It accepts a string and returns a boolean
+
+
+```
+
+
+## Methods
+```
+show ()                         Show the lockscreen
+hide ()                         Hide the lockscreen
+```
+
+## Events
+```
+none
+```
+
+## Examples
+
+Here are two examples.  The first shows the lock screen.  The second uses the cordova device pause/resume events to show it
+
+```
+var lock=$(document.body).lockScreen();
+lock.validatePassword=function(pass){
+    pass=parseInt(pass,10);
+    return pass==1111;
+}
+lock.show();
+```
+
+Now we force showing on the cordova device pause/resume events
+
+```
+
+function showLockScreen(){
+    var lock=$(document.body).lockScreen();
+    lock.validatePassword=function(pass){
+        pass=parseInt(pass,10);
+        return pass==1111;
+    }
+    lock.show();
+}
+
+$(document).on("pause resume",showLockScreen,false);
+
+```