Drupal 9 compatibility.
Readme updates and Drupal 9 compatibility
#1793542 - Add support for Robots #1793518 - Avoid outputing tags with empty values
#1765294 - Allow overriding the H1 title #1653344 - Token support
Stable branch for Drupal 7
Drupal 7 upgrade
Initial release - V1
added pagetitle and nodewords module compatability