Add guide when signing key is not found

[mlsmaycon]

Describe your changes

Some users face issues with their IdP due to signing key not being refreshed

With this change we advise users to configure key refresh

Issue ticket number and link

Checklist

• [ ] Is it a bug fix
• [ ] Is a typo/documentation fix
• [ ] Is a feature enhancement
• [ ] It is a refactor
• [ ] Created tests that fail without the change (if possible)
• [ ] Extended the README / documentation, if necessary

[sonarcloud[bot]]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud