Add the ability to pull a README.md's raw HTML into external applications

Problem/Motivation

Even though all README files are available via the Drupal admin UI, many development teams use external wikis to maintain their documentation. The README files should be available via a secure tokenized URL so that a wiki can dynamically include the generated HTML.

Proposed resolution

Provide URLs to README HTML file that can only be accessed by using a secure token.

Remaining tasks

• Create admin settings form to manager token
• Generate token when module is installed
• Write update hook to generate token
• Create '/admin/readme/{name}/html' routes
• Provide link to raw HTML on '/admin/readme/{name}' pages

Development Notes

• Branch Name: 2750359-readme-raw-html
• Commit message: Issue #2750359: Add the ability to pull a README.md's raw html into external applications.