Extend documentation to explain about plumber deployment in AWS Lambda/Azure functions

[adisarid]

I think that adding a section on deploying to either AWS Lambda or Azure functions will be extremely beneficial. Probably somewhere here: https://github.com/rstudio/plumber/blob/92532ffc1d7188b2841235dc4416178c57e51b8e/vignettes/hosting.Rmd#L2

If not a complete documentation, you might consider mentioning the option to go serverless in those services, and also some words about how that changes the interaction with the API (I'm guessing that since you go through API gateway, some things change?)

It looks like this post touches the point, but is not a formal self-contained documentation of this option.