Fix bullet in History.

Author: drbrain

History.rdoc

@@ -13,7 +13,7 @@
   * Running rake for the first time now installs racc.  Pull request #285 by
     Kouhei Sutou.
   * Added <code>-h</code> flag to also display help.  Issue #300 by Ryan Davis
-    search_index.js is now loaded asynchronously for improved performance.
+  * search_index.js is now loaded asynchronously for improved performance.
   * Allow +X::Y+ as typewriter text.  Issue #319, pull request #322 by Jeremy
     Evans.
   * Added RDoc::RI::Task for building ri data easily through rake.  Pull