Define preferred style for wrapping and enforce with linter

[joshuagl]

Discussed during review of #163 (#163 (comment)) we should define a stance on wrapping and add a linter to ensure pull requests conform to the preferred style.

@mnm678 expressed a desire to support line-wrapping at sentences as is done in OCI specs (see https://github.com/opencontainers/image-spec#markdown-style), rather than a strict character limit.

Are there linters which support this option? When SLSA looked in mid 2021 we could not easily find something (see slsa-framework/slsa#75).