Docs: Add elastics-rb to the list of community clients

Closes #8319

docs/community/clients.asciidoc

@@ -50,6 +50,9 @@ See the {client}/ruby-api/current/index.html[official Elasticsearch Ruby client]
 
 * https://github.com/ddnexus/flex[Flex]:
   Ruby Client.
+  
+* https://github.com/printercu/elastics-rb[elastics]:
+  Tiny client with built-in zero-downtime migrations and ActiveRecord integration.
 
 
 [[community-php]]