Add /camo/ to robots.txt

Camo only proxies images hosted somewhere else, so it doesn't make sense
to add the proxied versions to search engines. It only creates traffic
for camo when /camo/* urls are in search results.

closes #7726

Changelog.md

@@ -3,6 +3,7 @@
 ## Refactor
 * Don't print a warning when starting the server outside a Git repo [#7712](https://github.com/diaspora/diaspora/pull/7712)
 * Make script/server work on readonly filesystems [#7719](https://github.com/diaspora/diaspora/pull/7719)
+* Add camo paths to the robots.txt [#7726](https://github.com/diaspora/diaspora/pull/7726)
 
 ## Bug fixes
 * Prevent duplicate mention notifications when the post is received twice [#7721](https://github.com/diaspora/diaspora/pull/7721)

public/robots.txt

@@ -8,3 +8,4 @@
 User-Agent: *
 Disallow: /people/
 Disallow: /u/
+Disallow: /camo/