Add metric for checking common documentation paths

[d33bs]

Description

This PR adds a metric which checks for "common documentation" paths within a given repository. We perform this measurement in alignment with #150. As part of measuring how the Almanack itself meets this standard I created a docs directory with a reference to where to find the documentation for this project. As a minor note to this effect, the book content is currently stored within the src as it is included with the package builds for reading through the Python package.

I feel we could continue to work on #150 with another change after this which involves looking at common GitHub Pages locations based on the git remotes listing of a repository (which would likely yield an HTTP link we could use to form the default GitHub pages default). We could also check for docs badging within the main readme. Either way, I thought these changes might be better outside this PR, as they're a bit different in nature.

References #150

What is the nature of your change?

• Content additions or updates (adds or updates content)
• Bug fix (fixes an issue).
• Enhancement (adds functionality).
• Breaking change (these changes would cause existing functionality to not work as expected).

Checklist

Please ensure that all boxes are checked before indicating that this pull request is ready for review.

• I have read the CONTRIBUTING.md guidelines.
• My code follows the style guidelines of this project.
• I have performed a self-review of my own contributions.
• I have commented my content, particularly in hard-to-understand areas.
• I have made corresponding changes to related documentation (outside of book content).
• My changes generate no new warnings.
• New and existing tests pass locally with my changes.
• I have added tests that prove my additions are effective or that my feature works.
• I have deleted all non-relevant text in this pull request template.

[falquaddoomi]

Checking for documentation seems useful, cheers to that. 😄 AFAICT there weren't any issues with your code, but I made a few comments that I hoped might help simplify it by leveraging existing functionality in the libraries you're using.

[d33bs]

Thanks @falquaddoomi for the review! I've addressed your comments with various updates. Please let me know if there's anything else I may do to help meet an approval for this PR.

[falquaddoomi]

Looks good to me!

[d33bs]

Thanks @falquaddoomi ! Merging this in now.