Merge pull request #1051 from jcstr/patch2-docs

Add python 3 use case

Author: lukpueh

docs/CLI.md

@@ -283,6 +283,11 @@ $ cd tufrepo/
 $ python -m SimpleHTTPServer 8001
 ```
 
+If running python 3:
+```Bash
+$ python3 -m http.server 8001
+```
+
 ```Bash
 Step (4)
 $ client.py --repo http://localhost:8001 README.txt
@@ -411,6 +416,11 @@ $ cd tufrepo/
 $ python -m SimpleHTTPServer 8001
 ```
 
+If running python 3:
+```Bash
+$ python3 -m http.server 8001
+```
+
 Fetch the role x's README.txt
 ```Bash
 $ client.py --repo http://localhost:8001 README.txt