Examples: minor fixes and enhancements for ContactPerson examples for SAML backend and frontend

[vladimir-mencl-eresearch]

Hi @c00kiemon5ter ,

I was tweaking the configuration of my instance to create metadata that passes the tests run by the eduGAIN metadata validator.

Two minor contributions:

• prefix email address with "mailto" to make it a valid URI
• add an example for a REFEDS Security Contact. It was a bit of a challenge to get the config right, so I thought it might be worth sharing.

Please let me know whether you're happy to merge this.

Cheers, Vlad

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[c00kiemon5ter]

thank you!