Merge branch 'jm-gromacs-easyblock' into '2022'

Added README entry for custom EasyBlock gromacs.py.

See merge request hps-public/easybuild-repository!1099

Custom_EasyBlocks/README.md

@@ -67,3 +67,8 @@ Overview of the custom EasyBlocks.
 - __*difference compared to upstream*__ upstream checks for Mesa inside the easyblock
 - __*can not be removed*__ once upstream uses our OpenGL module
 
+## GROMACS
+- __*added_by*__ j.meinke
+- __*needed because*__ want to use easyconfig parameters to determine CUDA capability.
+- __*difference compared to upstream*__ upstream doesn't have such a feature
+- __*can not be removed*__ until merged upstream