Update z03-data-binding.md

Author: twolfe2

z03-data-binding.md

@@ -308,7 +308,7 @@ nextrects.enter().append('rect'); // adds one element
 
 ## Transitions `selection.transition()`
 
-The key function <isindex></isindex> also important in case parts of our objects change -- if we
+The key function is also important in case parts of our objects change -- if we
 change a count, then we can update the appropriate element without having to
 delete and re-add the element, we can update it in place.
 
@@ -477,4 +477,4 @@ mostly build on what we've already shown.
 </a>
 
 
-<script type="text/javascript" src="{{ "/javascripts/data-binding.js" | prepend: site.baseurl }}"></script>
+<script type="text/javascript" src="{{ "/javascripts/data-binding.js" | prepend: site.baseurl }}"></script>