Merge pull request #130 from NREL/add-demo-to-readme-fsim2

updating fastsim-2 readme to include instructions for downloading demo files

README.md

@@ -56,7 +56,12 @@ Developers might want to install the code in place so that FASTSim files can be
 
 ## Usage
 
-To see and run examples, navigate to `./python/fastsim/demos` and run the various *demo.py files to see fastsim use cases. There are other examples in fastsim/tests.  
+To see and run examples, download the FASTSim demo files using the following code (with your Python environment activated and FASTSim installed):
+```python
+from fastsim import utils  
+utils.copy_demo_files()
+```
+This code downloads demo files into a specified local directory (if no directory is specified, it will create a `\demos` folder in the current working directory). WARNING: If you download the demo files to a location where files of the same name already exist, the original files will be overwritten.  
 
 ## Adding FASTSim as a Dependency in Rust