regenie 2.2.4 is documented at csd3

See https://cambridge-ceu.github.io/csd3/applications/regenie.html?highlight=regenie

NOTES

This follows the publication of the UKB exome paper, Exome sequencing and analysis of 454,787 UK Biobank participants, https://www.nature.com/articles/s41586-021-04103-z