Prepare Webdoc 2.2.1 patch release

[ShukantPal]

Stack position

This is stack item 3 of 3. It is based on master and should merge after: (1) CI baseline and (2) dependency modernization. It intentionally does not modify CI workflows or third-party dependency versions; the only dependency-range edits are Rush-generated @webdoc/* lockstep release updates.

Release preparation

• Bumps the 12 Rush-publishable @webdoc/* packages from 2.2.0 to the lockstep patch release 2.2.1.
• Generates Rush changelog entries for the unreleased post-2.2.0 fixes: Add missing URL scheme #196 layout URL schemes in both templates and Update version.number in defaultConfig #197 CLI default version number.
• Records maintenance status and supported migration paths for legacy @webdoc/parser, @webdoc/example, and @webdoc/tests. No package was published, deprecated, or removed.

Owner publish command (after merge)

From a supported Node.js version with npm credentials configured, run:

node common/scripts/install-run-rush.js publish --publish --include-all --version-policy webdoc

This publishes the already-prepared 2.2.1 versions; do not run rush version again first.

Legacy npm custody recommendation — owner decision required

• @webdoc/parser (1.6.6, ~2,893 monthly downloads): recommend npm deprecate with a migration message to @webdoc/language-parser; the successor is maintained in Rush and the deprecation preserves installs while giving consumers a clear route.
• @webdoc/example (1.0.0, ~220/month): recommend npm deprecate; it is an unpublished reference-only example, and consumers should use @webdoc/cli plus copied configuration patterns.
• @webdoc/tests (1.0.0, ~108/month): recommend npm deprecate; it is an unmaintained integration fixture outside the Rush project list, and consumers should use root Rush test commands or @webdoc/cli public APIs.

These are recommendations only. This PR deliberately does not invoke npm deprecate.