Update accessing-context.md

the order of the two commands when cloning the repo and then starting the services is corrected

Author: yalpayelekon

docs/accessing-context.md

@@ -225,8 +225,8 @@ clone the repository and create the necessary images by running the commands as
 ```bash
 #!/bin/bash
 git clone https://github.com/FIWARE/tutorials.Accessing-Context.git
-git checkout NGSI-v2
 cd tutorials.Accessing-Context
+git checkout NGSI-v2
 
 ./services create; ./services start;
 ```