Upgrading.md

@@ -26,7 +26,7 @@
     other consumers
 * Fixes  and  cleanups in  the  low-level socket  code  -  make the  2
   implementations  more   alike,  ensure  that  all   sockets  are  in
-  no-blocking mode and use select() to do blocking reads / writes.
+  non-blocking mode and use select() to do blocking reads / writes.
 * Stability fixes to better handle unexpected socket closure
 * Some more features for the demo scripts