Expose Markdown validation selection

docs/consumers/check.md

@@ -62,6 +62,20 @@ directories; excluded directories include descendants. Symlink blobs are
 measured by link-text bytes, and gitlinks are omitted. The check applies to the
 captured candidate and reports one oversized file with its measurement as
 `file-size`; it does not measure historical or aggregate size.
+Set `Validation.Markdown` to check committed local Markdown destinations and
+supported heading fragments. Nil disables the check; an empty object enables
+it with outside-checkout destinations reported as out of scope. Set
+`EnforceCheckoutBoundary` to fail outside-checkout links. Submodule contents
+remain out of scope under either setting. The checker runs after file-size
+inspection and before `AdditionalChecks`; its nonfailure observations use the
+request's output writer. Markdown failures use the `markdown-links` identity
+and include the source location and destination.
+
+Use these selections for ReleaseKit-owned validation rather than repeating the
+standard suite, selected vet/format/distribution checks, or Markdown navigation
+checks in `AdditionalChecks` or profile `checks`. Keep release-note rules and
+consumer-specific assertions—such as tests of maintained examples—in those
+product-owned checks.
 ReleaseKit calls `AdditionalChecks` once after shared validation when supplied.
 It does not download a different toolchain automatically. If race prerequisites
 are unavailable, the `go-test` check fails rather than being skipped; a selected

docs/consumers/publish.md

@@ -78,6 +78,19 @@ blob size is its link text; gitlinks are omitted. This check measures only the
 captured candidate and reports one oversized file with its measurement as
 `file-size`; it stops publication before product checks or tag creation.
 
+Set `Validation.Markdown` to check committed local Markdown destinations and
+supported heading fragments during publication. Nil disables the check; an
+empty object enables it with outside-checkout links reported as out of scope.
+Set `EnforceCheckoutBoundary` to fail those links. Submodule contents remain
+out of scope under either setting. Observations use the request's output writer;
+failures use `markdown-links` and stop publication before product checks or tag
+creation.
+
+ReleaseKit-owned selections replace duplicate generic suite, vet, formatting,
+distribution, and Markdown checks in configured product checks. Keep
+release-note rules and consumer-specific assertions, such as maintained-example
+tests, in `AdditionalChecks` or profile `checks`.
+
 If `Build` selects targets, ReleaseKit verifies them after the standard suite
 and additional checks, before creating the tag. The operation then rechecks the
 candidate and remote guards, creates an annotated tag for the captured commit,