Merge pull request #19 from ClarkCGA/v20

Add citation section to README

Merge pull request #13 from ClarkCGA/tawoodard-patch-1

Update README.md

Merge pull request #13 from ClarkCGA/tawoodard-patch-1

Update README.md

Merge pull request #9 from ClarkCGA/tawoodard-patch-1

Update README.md

Update README.md releasing v.20.01

releasing v.20.01

updated links in README

added v19 installation

added version