Update description and keywords

package.json

@@ -1,7 +1,7 @@
 {
   "name": "expired",
   "version": "0.1.0",
-  "description": "Calculate when HTTP cache headers expire",
+  "description": "Calculate when HTTP responses expire from the cache headers",
   "main": "src/index.js",
   "scripts": {
     "test": "nyc ava",
@@ -13,12 +13,14 @@
     "url": "git+https://github.com/lukechilds/expired.git"
   },
   "keywords": [
+    "calculate",
     "HTTP",
-    "cache",
-    "headers",
-    "expire",
+    "response",
     "expires",
-    "expirey"
+    "expire",
+    "expirey",
+    "cache",
+    "headers"
   ],
   "author": "Luke Childs <lukechilds123@gmail.com> (http://lukechilds.co.uk)",
   "license": "MIT",