Update README

[cyamonide]

This PR updates the README to include explanations on input/output, examples, and links to other helpful references.

🚧 do not merge - still testing examples for correctness
All examples are tested.

[gagoar]

looks really good. I wonder if you could include the defaults we are providing already in the action.yml

[cyamonide]

looks really good. I wonder if you could include the defaults we are providing already in the action.yml

@gagoar sure - I'll add required and defaults.

Question about the credentials fields:

Is it true that if a user wanted to provide a session token instead of the access key ID/secret access key pair, they wouldn't be able to because the ID/secret pair is required?

[gagoar]

looks really good. I wonder if you could include the defaults we are providing already in the action.yml

@gagoar sure - I'll add required and defaults.

Question about the credentials fields:

Is it true that if a user wanted to provide a session token instead of the access key ID/secret access key pair, they wouldn't be able to because the ID/secret pair is required?

the configuration ask you for that right now, we can change that just changing the required: false

also this is why I've configure them that way, https://docs.aws.amazon.com/sdk-for-javascript/v2/developer-guide/loading-node-credentials-environment.html

[gagoar]

@cyamonide the signature for the sdk doesn't make the accessKeyId or secretAccessKey optional.

I think the sessionToken is optional, because when it fetches something it will sign the request with the session token if present, but it will not remove the need for the other 2 attributes.

[gagoar]

when you are writing your examples do you mind testing it with invoke-aws-lambda@master instead of using v3?