docs(commit.md): add documentation for always_signoff config setting

Author: schlotter

docs/commit.md

@@ -12,5 +12,20 @@ write the message to a file and not modify files and create a commit. A possible
 case for this is to [automatically prepare a commit message](./tutorials/auto_prepare_commit_message.md).
 
 !!! note
-    To maintain platform compatibility, the `commit` command disable ANSI escaping in its output.
-    In particular pre-commit hooks coloring will be deactivated as discussed in [commitizen-tools/commitizen#417](https://github.com/commitizen-tools/commitizen/issues/417).
+    To maintain platform compatibility, the `commit` command disables ANSI escaping in its output.
+    In particular, pre-commit hooks coloring will be deactivated as discussed in [commitizen-tools/commitizen#417](https://github.com/commitizen-tools/commitizen/issues/417).
+
+## Configuration
+
+### `always_signoff`
+
+When set to `true`, each commit message created by `cz commit` will be signed off.
+
+Defaults to: `false`.
+
+In your `pyproject.toml` or `.cz.toml`:
+
+```toml
+[tool.commitizen]
+always_signoff = true
+```