docs(bump): document usage of the update_changelog_on_bump flag

Author: Jan Willhaus

docs/bump.md

@@ -64,6 +64,7 @@ optional arguments:
   --dry-run             show output to stdout, no commit, no modified files
   --files-only          bump version in the files from the config
   --changelog, -ch      generate the changelog for the newest version
+  --no-changelog, -nch  do not generate changelog when config defaults to doing so
   --no-verify           this option bypasses the pre-commit and commit-msg
                         hooks
   --yes                 accept automatically questions done
@@ -90,6 +91,14 @@ Generate a **changelog** along with the new version and tag when bumping.
 cz bump --changelog
 ```
 
+### `--no-changelog`
+
+Disable generating a **changelog** along with the new version. This is useful when `update_changelog_on_bump` configuration option is set but should be disabled for the new version.
+
+```bash
+cz bump --no-changelog
+```
+
 ### `--check-consistency`
 
 Check whether the versions defined in `version_files` and the version in commitizen
@@ -216,6 +225,19 @@ Some examples
 bump_message = "release $current_version → $new_version [skip-ci]"
 ```
 
+---
+
+### `update_changelog_on_bump`
+
+When set to `true` the changelog is always updated incrementally when running `cz bump`, so the user does not have to provide the `--changelog` flag every time.
+
+defaults to: `false`
+
+```toml
+[tool.commitizen]
+update_changelog_on_bump = true
+```
+
 ## Custom bump
 
 Read the [customizing section](./customization.md).