Correct the rule count in the GitHub About description #80

Problem

The repository's About description says "228 hand-picked rules in one import", but the rule set ships 216 rules: rules/rules.php lists 216 classes and composer.json says 216.

It also says "with every other rule listed as skipped". That list lives in build/ and is not part of what Composer installs, so a reader of the package never sees it.

Proposal

Update the About description to the real count and drop or reword the "listed as skipped" claim, for example:

Curated Rector rule set for PHP 8.4+ — 216 hand-picked rules in one import.

The About box is a repository setting, so this needs a maintainer to apply it.

Found while aligning the README with the shared README standard (#79).