Linting

[tkphd]

This PR corrects a few typographical errors, addresses issues raised by MarkdownLint and YamlLint, harmonizes line wrapping to the "semantic-and-length" style demonstrated in CONTRIBUTING.md, and appends missing new-lines where needed for POSIX compliance. To help remove some tedium from maintaining this style, a basic .editorconfig is provided.

[github-actions[bot]]

:warning: WARNING :warning:

This pull request contains a mix of workflow files and regular files. This could be malicious. No preview will be created.

regular files:

• .editorconfig
• .gitignore
• CODE_OF_CONDUCT.md
• CONTRIBUTING.md
• LICENSE.md
• README.md
• config.yaml
• episodes/introduction.md
• index.md
• instructors/instructor-notes.md
• learners/reference.md
• links.md
• profiles/learner-profiles.md
• site/README.md

workflow files:

• .github/workflows/README.md
• .github/workflows/pr-close-signal.yaml
• .github/workflows/pr-comment.yaml
• .github/workflows/pr-post-remove-branch.yaml
• .github/workflows/pr-preflight.yaml
• .github/workflows/pr-receive.yaml
• .github/workflows/sandpaper-main.yaml
• .github/workflows/update-cache.yaml
• .github/workflows/update-workflows.yaml

[tkphd]

Thanks for the feedback @zkamvar. I can split the edits between separate workflow and regular file PRs, address your comments in the process, and make PRs against the upstream repo(s) where appropriate.