Merge pull request grpc#22840 from efimki/patch-1

Fix spelling error

Author: stanley-cheung

src/objective-c/NetworkTransitionBehavior.md

@@ -26,7 +26,7 @@ The expected gRPC iOS channel and network transition behaviors are:
   During the backoff period, any call to the same host will wait until the
   first of the following events occur:
     * Connection succeeded; calls will be made using this channel;
-    * Conncetion failed; calls will be failed and return UNAVAILABLE status code;
+    * Connection failed; calls will be failed and return UNAVAILABLE status code;
     * The call's deadline is reached; the call will fail and return
       DEADLINE\_EXCEEDED status code.
   The length of backoff period of a channel is reset whenever a connection