Deleted repeated "safe" and fixed typo in definition of "safe zone" (#…

…720)

index.html

@@ -2530,7 +2530,7 @@ <h3>
             <dfn data-lt="badge maskable">maskable</dfn>:
           </dt>
           <dd>
-            The image is designed with <a href="#icon-masks">icon masks and safe
+            The image is designed with <a href="#icon-masks">icon masks and
             safe zone</a> in mind, such that any part of the image that is
             outside the <a>safe zone</a> can safely be ignored and masked
             away by the user agent.
@@ -2625,7 +2625,7 @@ <h2><a id="icon-masks"></a>
           preferences. It is defined as a circle with center point in the center
           of the icon and with a radius of 2/5 (40%) of the icon size, which means
           the smaller of the icon width and height, in case the icon is not
-          rectangular.
+          square.
         </p>
         <p class="note">
           Designers of <a>maskable</a> icons will want to make sure that all