Remove "bootstrap" keyword

composer.json

 {
   "name": "twbs/bootstrap",
   "description": "Sleek, intuitive, and powerful mobile first front-end framework for faster and easier web development.",
-  "keywords": ["bootstrap", "css"],
+  "keywords": [
+    "css"
+  ],
   "homepage": "http://getbootstrap.com",
   "authors": [
     {