Update README.md

README.md

@@ -13,6 +13,7 @@ This subset includes 21799 ECG images that have been generated directly from the
 This subset contains the same 21799 ECG images as Dataset A, but with added visual imperfections that simulate common issues found in photographed ECGs.
 
 The original PTB-XL metadata can be found in the CSV file: https://physionet.org/content/ptb-xl/1.0.3/ptbxl_database.csv
-Images in the GenECG dataset have the same ecg_id as the PTB-XL dataset.
+Images in the GenECG dataset have the same ecg_id as the PTB-XL dataset with the addition of _hr_1R to the ECG ID.
+For example, ECG 02000_hr_1R.png from GenECG corresponds to 02000_hr.dat in PTB-XL. 
 
 For more information about the creation of GenECG, please refer to the following publication: DOI: XXX