Update SETUP.md

SETUP.md

+# Download
+
+You can download the tutorials with `git` with the following command (it should be public):
+
+```
+git clone https://git.scc.kit.edu/sp2668/esm_tutorials.git
+```
+
+Alternatively, you can download the tutorials as compressed folder.
+
 # Installation Guide
 
 Install `miniconda` (or Anaconda). For instructions for your operating system see
@@ -22,7 +32,7 @@ source activate esm-tutorials
 conda list
 ```
 
-Open a jupyter notebook with the following command:
+Open a jupyter notebook with the following command in the tutorial folder (where your notebooks are):
 ```
 jupyter notebook
 ```