chore(package): update documentation to version 6.1.0

Closes #4

Author: greenkeeper[bot]

package.json

@@ -22,7 +22,7 @@
   },
   "devDependencies": {
     "coveralls": "^3.0.0",
-    "documentation": "^5.3.5",
+    "documentation": "^6.1.0",
     "nyc": "^11.4.1",
     "standard": "^10.0.0",
     "tape": "^4.0.3"