feat(readme): detect and score GitHub (Enterprise) READMEs

[gregswindle]

1. User story summary

As a repository owner or maintainer, I want to ensure my product has a well-written README In order to introduce potential consumers to my product.

2. Acceptance criteria

When given the URL to a repository,

• [x] 1. The presence of a README is declared.
• [x] 2. The absence of README is declared.
• [x] 3. READMEs are scored according to the readme-score-api (as used by the CoCoPods registry).
• [x] 4. Configuration variables are separated from source code with environment (env) variables.

[gregswindle]

:tada: This issue has been resolved in version 1.0.0 :tada:

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot :package::rocket: