docs(ie): document IE style attribute interpolation problem

IE has issues with this, it's good to make a note of this.

Closes #6329

Author: Richard Collins

docs/content/guide/ie.ngdoc

@@ -77,6 +77,9 @@ To make your Angular application work on IE please make sure that:
          </body>
        </html>
      ```
+  5. Use `ng-style` tags instead of `style="{{ someCss }}"`. The later works in Chrome and Firefox
+     but does not work in Internet Explorer <= 11 (the most recent version at time of writing).
+     
 
 The **important** parts are: