Add documentation for package scanner

The package scanner really needs to have its documentation page filled out:
https://docs.chocolatey.org/en-us/community-repository/moderation/package-scanner

Here things I would like to see:
- What the size limit is for binaries, and how it shows up if a binary is too large.
- Information about how and why packages cannot be approved if the scanner has been exempted
- Information about how the scanner works with regards to what will break the scanning (number of scanned files doesn't match the number of expected files), how to write packages that don't break the scanner, and how it shows up as if the package has broken the scanner

Start with the package scanner documentation page linked in the issue and review the existing documentation structure. Research and document the binary size limit and failure display, scanner exemptions and approval behavior, file-count mismatches, package-writing guidance, and how scanner breakage is reported; the page is done when all requested behaviors are explained.

Written by the indexing model from the issue text.