Consider unified option for controlling what features are required

[bmish]

Now that we provide the following features:

• README.md rules table
• README.md configs table
• Rule doc titles and notices
• Rule doc options lists

We may need to offer an option to control which are mandatory (i.e. exit with failure if missing) or automatically-inserted when missing.

And we will likely want to require all or most of these features as a breaking change in a future major release.

There's an existing --rule-doc-section-options option that controls whether this section is required but doesn't control whether the auto-generated options list in it is required.