docs: initial configuration documentation

[claymcleod]

This pull request introduces an initial draft of the configuration documentation. It's still a work in progress, but feel free to review the existing content.

Before submitting this PR, please make sure:

• You have added a few sentences describing the PR here.
• You have added yourself or the appropriate individual as the assignee.
• You have added at least one relevant code reviewer to the PR.
• Your code builds clean without any errors or warnings.
• You have added tests (when appropriate).
• You have updated the README or other documentation to account for these
  changes (when appropriate).
• You have added an entry to the relevant CHANGELOG.md (see
  "keep a changelog" for more information).
• Your commit messages follow the conventional commit style.