Add documentation about changes in fastify.jwt object while using namespaces

[jmartinacu]

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Issue

Hello, I was using fastify-jwt to implement a authorization strategy with accessToken and refreshToken using the namespace feature.
But when I had to use the functionality of fastify.jwt instead of the default function <namespace>JwtVerify or <namespace>JwtSign defined in the documentation, there wasn't any information about the changes that are applied to fastify.jwt when you use namespaces.

[Eomm]

Thanks for reporting!
Would you like to send a Pull Request to address this issue?

[piotr-cz]

The documentation has been updated along with #297.
It may cover your issue

[limtis0]

I suppose it would be good to know about how to use .jwtVerify() with namespaces, because all of the .{namespace}JwtVerify functions require token: string, contrary to the default function (They are bound to FastifyInstance, instead of FastifyRequest, as well). It is also unclear on how to use it with cookies, for example.

I can set up a new Issue if this is not an intended behavior.

[mahmoodhamdi]

I ran into this same gap while setting up access + refresh tokens with namespaces. Opened a PR to document how fastify.jwt changes when using namespaces: #398

It covers the fact that fastify.jwt becomes a keyed object (fastify.jwt.access.sign(), fastify.jwt.refresh.verify(), etc.) instead of the direct utility, and includes a practical example.