Docs: Update readme

Author: tstenner

README.md

@@ -12,5 +12,6 @@ This is the MATLAB interface for liblsl.
 ### Troubleshooting
 
 If you get an error similar to `lsl_loadlib_ undefined`, then you may need to run the `build_mex.m` script from within the liblsl-Matlab directory.
+(From the command line: `matlab -nodesktop -nosplash -r 'build_mex'`)
 
 On MacOS, you may still get an error similar to `Invalid MEX-file [...] lsl_loadlib_.mexmaci64; Reason: image not found.`. To fix this run the following command in a Terminal window from within the liblsl-Matlab directory: `install_name_tool -add_rpath "@loader_path/" bin/lsl_loadlib_.mexmaci64`