Update the JWT Policy documentation so that it is clear that it supports automatic rolling over JWKS

[sjanssens1977]

🌈 Feature

As a API publisher I use the policy documentation to evaluate the functionalities offered by a policy. This information should be kept up-to-date at all times.

I want to be able to make opinionated decisions based on the information provided by the documentation.

So that I do not have to try-out every policy during the design phase and can make good design decisions.

🌄 Additional information

The current policy documentation is lacking information about the ability to use a Oauth2 JWKS URL to retrieve the public keys used
for signing. Based on the documentation I concluded that the policy did not support rollover JWKS.

The policy prompts you to choose between three (GIVEN_KEY, GIVEN_ISSUER, GATEWAY_ISSUER) methods to retrieve the required public key.

✅ Acceptance criteria

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☑️ Developer sub-tasks

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[brasseld]

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