Auto-generate README.mds from source files

[JoshuaKGoldberg]

Requires #7.

README files should contain something like:

• Name - Taken from package.json name
• Short description - Taken from package.json description
• Paragraph(s) description - Taken from {RepoName}.ts
• Examples of usage - Taken from class {RepoName}'s JSDoc examples
• Examples for each public function - Taken from each public function's JSDoc examples