Improvements to the "Using Macaron" page on Macaron HTML documentation

[nathanwn]

Currently, the "Using Macaron" page on the Macaron HTML documentation has a few issues. Possible improvements include:

• Clearly separating different use cases of Macaron into top-level sections: There should be one top-level section for macaron analyze and another top-level section for macaron verify-policy. Within each top-level section, there can be subsections explaining different options for that action/use case.
• Focusing on communicating the use case as opposed to lower-level details in the section headings.

The outline may look like the following:

1. Analyze the SLSA posture of a repository
  1.1. Analyze a remote repository
  1.2. With an SBOM
  1.3. With provenance expectations (in cue lang)
  1.4. Analyze a local repository
2. Verify a repository against user-defined expectations (with souffle datalog policy engine)