mod_netconf: user given testopt value

add optional json parameter 'test-option' for edit-config
possible values are: "notset", "testset" (default), "set", "test"

- refs #1360
diff --git a/src/README b/src/README
index c7f5c8d..6300d20 100644
--- a/src/README
+++ b/src/README
@@ -103,6 +103,7 @@
 key: default-operation (string), value: merge|replace|none
 key: error-option (string), value: stop-on-error|continue-on-error|rollback-on-error 
 key: uri-source (string), required when "source" is "url", value: uri
+key: test-option (string), value: notset|testset|set|test, default value: testset
 
 6) NETCONF <copy-config>
 key: type (int), value: 9