updates to readme build

Signed-off-by: Alex McCaskey <mccaskeyaj@ornl.gov>

README.md

@@ -30,7 +30,9 @@ To enable Python support, ensure that `python3` is set to your desired version o
 find the corresponding development headers. Ensure that when you try to run XACC-enabled Python scripts
 you are using the same `python3` executable that was set during your build.
 
-If you are on Mac OS X, make sure you have XCode command utilities installed.
+If you are on Mac OS X, make sure you have XCode command utilities installed. A common issue seen
+is missing standard includes like `wchar.h` and others. See [here](https://stackoverflow.com/a/52530212)
+for proper XCode install and configuring to address these types of issues.
 
 Clone the repository recursively, configure with `cmake` and build with `make`
 ```bash