Updated Lambda runtimes (#421)
Updated Lambda runtimes (#421)

* Updated Lambda runtimes

Reviewed the available Lambda runtimes at https://docs.aws.amazon.com/lambda/latest/dg/lambda-runtimes.html and found significant differences as of 2019-11-21. Documented those updates.
Made the punctuation for all languages consistent.
Note that Rust isn't an officially supported runtime, but leaving it in for now.

* Update what-is-aws-lambda.md

AnomalyInnovations/serverless-stack-com,AnomalyInnovations/serverless-stack-com