Mention WPE's Open Source nature in the frontpage

It's already  mentioned in "Get WPE" section, but this would be good too.

index.html

@@ -300,7 +300,7 @@ <h1>
 Create simple and performant systems based on <strong>Web platform technologies.</strong>
 </h1>
 <p>
-A WebKit port for Linux-based embedded devices designed with flexibility and hardware acceleration in mind, leveraging common 3D graphics APIs for best performance.
+A Open Source WebKit port for Linux-based embedded devices designed with flexibility and hardware acceleration in mind, leveraging common 3D graphics APIs for best performance.
 </p>
 <a class="cta btn large" href="/about/get-wpe.html">Get WPE</a>
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