Mention that driver is sync in README

bigbes · bigbes · commit 49658d9fbb26 · 2016-06-28T16:14:11.000+03:00
diff --git a/README.rst b/README.rst
@@ -76,6 +76,10 @@ See More
  * `Tarantool User Guide`_
  * `Client-server Protocol Specification`_
 
+NOTE
+^^^^
+
+This driver is synchronous, so connection mustn't be shared between threads/processes.
 
 .. _`Tarantool`:
 .. _`Tarantool Database`:
