Update README.md

Author: briandoyle81

README.md

@@ -58,6 +58,8 @@ buffer.get()   # should return ['d', 'e', 'f']
 
 #### Task 2. Runtime Optimization
 
+***!Important!*** If you are running this using PowerShell by clicking on the green play button, you will get an error that `names1.txt` is not found.  To resolve this, run it, get the error, then `cd` into the `names` directory in the `python` terminal that opens in VSCode.
+
 Navigate into the `names` directory. Here you will find two text files containing 10,000 names each, along with a program `names.py` that compares the two files and prints out duplicate name entries. Try running the code with `python3 names.py`. Be patient because it might take a while: approximately six seconds on my laptop. What is the runtime complexity of this code?
 
 Six seconds is an eternity so you've been tasked with speeding up the code. Can you get the runtime to under a second? Under one hundredth of a second?