Remove twitter's deprecated embedded search timeline

X/Twitter search timeline widget is no longer available.
Along with this, the words "Tweet about Vim" were displayed on the page
and a warning was displayed in the console.

This change removes those unnecessary and non-functional ones.

Author: koron

_includes/twitter-widget.html

@@ -47,6 +47,4 @@
 
 <br />
 
-{% include twitter-widget.html %}
-
 </div>