Update clone

Author: jason-fox

README.ja.md

@@ -155,6 +155,7 @@ FIWARE システム内の Generic Enabler として統合し、コンテキス
 ```console
 git clone https://github.com/FIWARE/tutorials.Media-Streams.git
 cd tutorials.Media-Streams
+git checkout NGSI-v2
 git submodule update --init --recursive
 
 ./services create

README.md

@@ -122,6 +122,7 @@ To start the installation, do the following:
 ```console
 git clone https://github.com/FIWARE/tutorials.Media-Streams.git
 cd tutorials.Media-Streams
+git checkout NGSI-v2
 git submodule update --init --recursive
 
 ./services create