Include an example/explanation about JWT refresh tokens

[khalibloo]

I imagine, in most cases, developers looking to add JWT authentication would be interested in learning about refresh tokens as well. The JWT article in the docs currently says that it is outside the scope of the article to discuss refresh tokens without saying why or giving alternatives. At the very least, an external resource explaining how one might go about implementing refresh tokens in NestJS should be linked.

I'm submitting a...

[ ] Regression 
[ ] Bug report
[ ] Feature request
[x] Documentation issue or request (new chapter/page)
[ ] Support request => Please do not submit support request here, instead post your question on Stack Overflow.

[kamilmysliwiec]

Lets track this here #1468