Bugfix/fix minor documentation issues

[ChristianUlbrich]

Fixes Issue #202, #115.

Description of changes:

• update README.md and some minor code examples to be consistent again, with current AWS infrastructure
  1. fix provided runtime to provided.al2023
  2. add missing --cli-binary-format raw-in-base64-out to make example work with current AWS CLI@2
  3. add hint on arm64 architecture
  4. fix example to use proper JSON (json payload here is not valid JSON)

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.