Docs: Add additional Lambda config recommendations.

[peterwilsoncc]

Add the following docs to the readme for configuration:

Runtime settings > Runtime handler: dist/lambda-handler.handler
Config > General > Timeout: What ever you recommend, the default is 3 seconds (I guessed at 1 minute)

Anything else you recommend such as memory, etc.

Additionally, Node 18 is no longer available via the console UI (not sure if it is via a config file), so are you able to document whether Node 20 or 22 is supported?

If you still recommend a cloudfront function to add the webp=1 query string for browsers that support it, dropping the code in the docs would be lovely too.