Document that Dependabot supports updates by commit and commit+tag/release (#41378)

Author: yeikel

data/reusables/actions/dependabot-version-updates-actions-caveats.md

@@ -1,3 +1,5 @@
-* {% data variables.product.prodname_dependabot %} only supports updates to {% data variables.product.prodname_actions %} using the {% data variables.product.prodname_dotcom %} repository syntax, such as `{% data reusables.actions.action-checkout %}`. {% data variables.product.prodname_dependabot %} will ignore actions or reusable workflows referenced locally (for example, `./.github/actions/foo.yml`).
+* {% data variables.product.prodname_dependabot %} only supports updates to {% data variables.product.prodname_actions %} using the {% data variables.product.prodname_dotcom %} repository syntax, such as `{% data reusables.actions.action-checkout %}` or `actions/checkout@<commit>` . {% data variables.product.prodname_dependabot %} will ignore actions or reusable workflows referenced locally (for example, `./.github/actions/foo.yml`).
+* {% data variables.product.prodname_dependabot %} updates the version documentation of {% data variables.product.prodname_actions %} when the comment is on the same line, such as `actions/checkout@<commit> #<tag or link>` or `actions/checkout@<tag> #<tag or link>`.
+* If the commit you use is not associated with any tag, {% data variables.product.prodname_dependabot %} will update the {% data variables.product.prodname_actions %} to the latest commit (which might differ from the latest release).
 * Docker Hub and {% data variables.product.prodname_registry %} {% data variables.product.prodname_container_registry %} URLs are currently not supported. For example, references to Docker container actions using `docker://` syntax aren't supported.
 * {% data variables.product.prodname_dependabot %} supports both public and private repositories for {% data variables.product.prodname_actions %}. For private registry configuration options, see "`git`" in [AUTOTITLE](/code-security/dependabot/dependabot-version-updates/configuration-options-for-the-dependabot.yml-file#git).