add keywords in root package.json (#2389)

Author: leibale

package.json

@@ -43,5 +43,8 @@
   "bugs": {
     "url": "https://github.com/redis/node-redis/issues"
   },
-  "homepage": "https://github.com/redis/node-redis"
+  "homepage": "https://github.com/redis/node-redis",
+  "keywords": [
+    "redis"
+  ]
 }