chore(docs): update to lunr-0.5.12

This improves the search results for certain terms.
For example, previously guide/scope was unfindable with the search
term 'scope', now it's the first hit.

Closes angular#12937

Author: Narretz

docs/app/assets/js/search-worker.js

@@ -3,7 +3,7 @@
 /* global importScripts, onmessage: true, postMessage, lunr */
 
 // Load up the lunr library
-importScripts('../components/lunr.js-0.4.2/lunr.min.js');
+importScripts('../components/lunr.js-0.5.12/lunr.min.js');
 
 // Create the lunr index - the docs should be an array of object, each object containing
 // the path and search terms for a page

docs/bower.json

@@ -2,7 +2,7 @@
   "name": "AngularJS-docs-app",
   "dependencies": {
     "jquery": "2.1.1",
-    "lunr.js": "0.4.3",
+    "lunr.js": "0.5.12",
     "open-sans-fontface": "1.0.4",
     "google-code-prettify": "1.0.1",
     "bootstrap": "3.1.1"