Mention sponsors + contributors on the front page

Author: wilzbach

index.dd

@@ -674,6 +674,10 @@ $(DIVC call_to_donate,
     <p class="center">
         <a href="$(ROOT_DIR)donate.html" class="btn call_to_donate_btn">Donate</a>
         <a href="$(ROOT_DIR)foundation.html" class="btn subdued">Learn More About The Foundation</a>
+        $(BR)
+        $(BR)
+        A huge $(WHY_D_ICON heart) to our $(LINK2 $(ROOT_DIR)sponsors.html, sponsors) and
+        $(LINK2 $(ROOT_DIR)contributors.html, contributors).
     </p>
 )