Add a few READMEs + linter script (#899)

* Add a few READMEs + linter script

* Add initial linter script

* Add CI job

* Apply suggestions from code review

Co-authored-by: John DiSanti <jdisanti@amazon.com>

* Add README fix command

* Add newline in footer

* Add footer support to generator

* Also run fixes in CI

* Add note about smithy-types

* cleanups to scripts and READMEs

Co-authored-by: John DiSanti <jdisanti@amazon.com>