v1.15.1

Changelog

• 01b7dff Fix descriptions to install terrascan (tenable#1254)
• ec6cae9 Rebranding repository to Tenable brand (tenable#1253)
• 9ae26fc Rebranding to Tenable (tenable#1246)
• 5d968e3 Update README.md (tenable#1245)
• fb1bbcc fix: remove master ref check from release docker push step (tenable#1244)
• feb646a nil pointer check to avoid panic (tenable#1260)
• 7126c48 release/v1.15.1 (tenable#1267)
• 48b6393 support reading terraformrc file from env var (tenable#1264)