maybe proactively redirect some doc site issues (facebook#11235)

* maybe proactively redirect some doc site issuesg

* Update ISSUE_TEMPLATE.md

Author: iamdustan

.github/ISSUE_TEMPLATE.md

@@ -1,3 +1,8 @@
+<!--
+  Note: if the issue is about documentation or the website, please file it at:
+  https://github.com/reactjs/reactjs.org/issues/new
+-->
+
 **Do you want to request a *feature* or report a *bug*?**
 
 **What is the current behavior?**