Merge pull request #994 from return42/add-limiter-redis-doc

[doc] add some documentation about the limiter plugin (and redis)

searx/plugins/limiter.py

@@ -3,6 +3,10 @@
 # pyright: basic
 """Some bot protection / rate limitation
 
+To monitore rate limits and protect privacy the IP addresses are getting stored
+with a hash so the limiter plugin knows who to block.  A redis database is
+needed to store the hash values.
+
 Enable the plugin in ``settings.yml``:
 
 - ``server.limiter: true``