Correct plugin format

Change-Id: I7e152cccaf9a11036f59cf99c5ffc0001ff412c2
diff --git a/experiments/netconf/yang2proto/yang2proto.py b/experiments/netconf/yang2proto/yang2proto.py
index 3808804..90b78e0 100644
--- a/experiments/netconf/yang2proto/yang2proto.py
+++ b/experiments/netconf/yang2proto/yang2proto.py
@@ -22,7 +22,7 @@
    - this plugin requires pyang to be present and is run using pyang as
    follows:
 
-   $ pyang --plugindir /voltha/experiments/netconf/yang2proto -f yang2proto  -o
+   $ pyang --plugindir /voltha/experiments/netconf/yang2proto -f proto  -o
    <protofile> -p /voltha/experiments/netconf/tests/yang2proto
    /voltha/experiments/netconf/tests/yang2proto/<yang file>