docs: update readme with commit description details

README.md

@@ -55,7 +55,7 @@ All inputs are **optional**. If not set, sensible defaults will be used.
 | `token` | `GITHUB_TOKEN` (permissions `contents: write` and `pull-requests: write`) or a `repo` scoped [Personal Access Token (PAT)](https://docs.github.com/en/github/authenticating-to-github/creating-a-personal-access-token). | `GITHUB_TOKEN` |
 | `path` | Relative path under `GITHUB_WORKSPACE` to the repository. | `GITHUB_WORKSPACE` |
 | `add-paths` | A comma or newline-separated list of file paths to commit. Paths should follow git's [pathspec](https://git-scm.com/docs/gitglossary#Documentation/gitglossary.txt-aiddefpathspecapathspec) syntax. If no paths are specified, all new and modified files are added. See [Add specific paths](#add-specific-paths). | |
-| `commit-message` | The message to use when committing changes. | `[create-pull-request] automated change` |
+| `commit-message` | The message to use when committing changes. See [commit-message](#commit-message). | `[create-pull-request] automated change` |
 | `committer` | The committer name and email address in the format `Display Name <[email protected]>`. Defaults to the GitHub Actions bot user. | `GitHub <[email protected]>` |
 | `author` | The author name and email address in the format `Display Name <[email protected]>`. Defaults to the user who triggered the workflow run. | `${{ github.actor }} <${{ github.actor }}@users.noreply.github.com>` |
 | `signoff` | Add [`Signed-off-by`](https://git-scm.com/docs/git-commit#Documentation/git-commit.txt---signoff) line by the committer at the end of the commit log message. | `false` |
@@ -74,6 +74,19 @@ All inputs are **optional**. If not set, sensible defaults will be used.
 | `milestone` | The number of the milestone to associate this pull request with. | |
 | `draft` | Create a [draft pull request](https://docs.github.com/en/github/collaborating-with-issues-and-pull-requests/about-pull-requests#draft-pull-requests). It is not possible to change draft status after creation except through the web interface. | `false` |
 
+#### commit-message
+
+In addition to a message, the `commit-message` input can also be used to populate the commit description. Leave a single blank line between the message and description.
+
+```yml
+          commit-message: |
+            the first line is the commit message
+
+            the commit description starts
+            after a blank line and can be
+            multiple lines
+```
+
 #### delete-branch
 
 The `delete-branch` feature doesn't delete branches immediately on merge. (It can't do that because it would require the merge to somehow trigger the action.)