Added do-while loop statement (#21611)

* Added do-while loop statement

* moved links to bottom, changed to markdown style links

guide/english/php/while/index.md

@@ -1,7 +1,8 @@
 ---
 title: While Loop
 ---
-## While Loops
+
+## While Loop
 A `while` loop executes statements within the loop as long as the loops condition is met. 
 
 ### Syntax:
@@ -16,5 +17,20 @@ while ($x < 11) {
 
 **Note:** The block code must have a statement that changes or increments the condition.  Otherwise an infinite loop could result.  
 
+
+Another loop statement is `do...while` where you execute your code at least once.
+
+### Syntax
+```php
+$x = 0;
+
+do {
+   ++$x;
+} while ($x < 11);
+```
+
+**Note:** Same as the `while` block, this should have a statement that changes, otherwise an infinite loop could result.
+
 ### More Information:
-<a href='http://php.net/manual/en/control-structures.while.php' target='_blank' rel='nofollow'>PHP While Loop</a> 
+- [PHP While Loop](http://php.net/manual/en/control-structures.while.php)
+- [PHP Do-While Loop](http://php.net/manual/en/control-structures.do.while.php)