Clarify info action's "search engine status"

Clarify info action's "search engine status"

We are using the word "indexing" anyway and I doubt the concept
of internal vs. external search engine is any more complex than
the concept of "robot" which also relates to robots.txt.
"Allowed" or "disallowed" also seems appropriate, as it describes
the permission without speaking of actual impossibility, though
some describe it as "preventing" indexing.

Examples:
http://www.robotstxt.org/meta.html
https://en.wikipedia.org/wiki/Noindex
https://support.google.com/webmasters/answer/93710?hl=en
http://googlewebmastercentral.blogspot.fi/2007/03/using-robots-meta-tag.html
https://developers.google.com/webmasters/control-crawl-index/docs/robots_meta_tag
http://www.w3.org/TR/html401/appendix/notes.html#h-B.4.1.2

Bug: 43935
Change-Id: I856767f9e4951b165b589a553dd84e35fc55822e