Reword README

Author: matthew-brett

README.md

@@ -38,7 +38,8 @@ This should print output to the terminal of form:
 
 Where `<filename>` is the name of the image that has outlier scans, and
 `<outlier_index>` is an index to the volume in the 4D image that you have
-identified as an outlier.  0 refers to the first volume.  For example:
+identified as an outlier.  0 refers to the first volume.  For example (these
+outlier IDs are completely random, for illustration):
 
 ```
 data/group-01/sub-01/func/sub-01_task-taskzero_run-01_bold.nii.gz, 3, 21, 22, 104