Automated linting of markdown documents via pre-commit and markdownlint-cli2

[ns-rse]

Issue 194 suggests linting the markdown documentation using markdownlint-cli2 via a pre-commit hook and integrated via pre-commit.ci so that checks are made when contributions are made.

[ns-rse]

See Pull request #195

Thanks @hturner and @njtierney for running todays session. 👍

[hturner]

Thanks for recording this work on the r-dev-day repo. We can follow up on your recommendations on the Dev Container repo.