You can use the link provided to download an updated SSL cert for the for VT Docs metadata.
https://visiblethread.s3.us-east-1.amazonaws.com/public/download/samlKeystore.jks
After downloading the cert run the below commands on your VT Docs server to apply the updated cert to the metadata.
Red Hat
systemctl stop visiblethread-docs.service
cp samlKeystore.jks /opt/visiblethread/tomcat/dashboard/VersionInfo
cp samlKeystore.jks /opt/visiblethread/tomcat/dashboard/WEB-INF/classes/VersionInfo
systemctl start visiblethread-docs.service
Ubuntu
systemctl stop supervisor
cp samlKeystore.jks /home/visiblethread/tomcat/dashboard/VersionInfo
cp samlKeystore.jks /home/visiblethread/tomcat/dashboard/WEB-INF/classes/VersionInfo
systemctl start supervisor
Windows
Press Windows Key and search for Services
In Service look for vtdocs-tomcat
Select it and Stop the service
copy samlKeystore.jks C:\Program Files\VisibleThread\vtdocs\tomcat\dashboard\VersionInfo
copy samlKeystore.jks C:\Program Files\VisibleThread\vtdocs\tomcat\dashboard\WEB-INF\classes\VersionInfo
Go back to Services after copying the new cert to the above locations and Start vtdocs-tomcat
The new cert should now be populated in the metadata.