When one would hit `ENTER` after filtering the list of examples, the form would
be submitted and the filter would be gone after the page reload. By giving the
main search field the appropriate `name`-attribute, this is being solved.
The original decision to avoid index.html was because it only works with a build step. Since we've all accepted a build step, the more sensible name is index.html. Without this change, every hosted example has a link to http://openlayers.github.com/ol3/master/examples/example-list.html which 404s.
