chore(package): update documentation to version 8.1.2

Closes #53

Author: greenkeeper[bot]

package.json

@@ -12,7 +12,7 @@
     "gulp": ">=3.0.0"
   },
   "devDependencies": {
-    "documentation": "^6.0.0",
+    "documentation": "^8.1.2",
     "gulp": "^3.9.1",
     "concat-stream": "^1.6.0",
     "cz-conventional-changelog": "^2.0.0",