update robots.txt

Author: CoderJackZhu

package.json

@@ -21,7 +21,6 @@
     "hexo-generator-feed": "^3.0.0",
     "hexo-generator-index": "^3.0.0",
     "hexo-generator-sitemap": "^3.0.1",
-    "hexo-generator-robots": "git+https://github.com/hexojs/hexo-generator-robots.git",
     "hexo-generator-tag": "^2.0.0",
     "hexo-renderer-ejs": "^2.0.0",
     "hexo-renderer-jade": "^0.5.0",

source/robots.txt

@@ -0,0 +1,3 @@
+User-agent: *
+Disallow:
+Sitemap: https://www.jackzhu.top/sitemap.xml