Formatting README, adding CONTRIBUTING.md, and markdown linting workflow #1

Annotations

10 errors

Line length [Expected: 80; Actual: 89]

Line length [Expected: 80; Actual: 89]

Line length [Expected: 80; Actual: 158]

Headings should be surrounded by blank lines [Expected: 1; Actual: 0; Below] [Context: "# Docker"]

Line length [Expected: 80; Actual: 182]

Lists should be surrounded by blank lines [Context: "- **fans-ci**: Contains the mi..."]

Line length [Expected: 80; Actual: 225]

Line length [Expected: 80; Actual: 324]

Headings should be surrounded by blank lines [Expected: 1; Actual: 0; Below] [Context: "## Set up a Container"]

Line length [Expected: 80; Actual: 255]