Disable crawling on Netlify. (#29193)

Gruntfile.js

@@ -291,7 +291,7 @@ module.exports = function (grunt) {
       docs: {},
       netlify: {
         options: {
-          raw: 'github: true\nbaseurl: ""'
+          raw: 'github: true\nbaseurl: ""\nnetlify: true'
         }
       },
       github: {

docs/robots.txt

@@ -3,7 +3,9 @@
 
 # www.robotstxt.org/
 
+{% if site.netlify != true and site.github == true -%}
 # Allow crawling of all content
+{%- endif %}
 User-agent: *
-Disallow:
+Disallow:{% if site.netlify == true or site.github != true %} /{% endif %}
 Sitemap: {{ site.url }}/sitemap.xml