doc: add usage and config to README.md

README.md

@@ -1 +1,70 @@
 # Vox Pupuli Commitlint Container
+
+[![CI](https://github.com/voxpupuli/container-commitlint/actions/workflows/ci.yaml/badge.svg)](https://github.com/voxpupuli/container-commitlint/actions/workflows/ci.yaml)
+[![License](https://img.shields.io/github/license/voxpupuli/container-commitlint.svg)](https://github.com/voxpupuli/container-commitlint/blob/main/LICENSE)
+[![Sponsored by betadots GmbH](https://img.shields.io/badge/Sponsored%20by-betadots%20GmbH-blue.svg)](https://www.betadots.de)
+
+This container can be used to lint commits.
+It encapsulates [commitlint](https://github.com/conventional-changelog/commitlint) and all necessary plugins.
+See [package.json](package.json) for details. This is a npm application running in an alpine container.
+
+## Usage
+
+### Lint last commit only
+
+```shell
+podman run -it --rm -v $PWD:/data ghcr.io/voxpupuli/commitlint:latest
+# or (but thats the default)
+podman run -it --rm -v $PWD:/data ghcr.io/voxpupuli/commitlint:latest --last
+```
+
+### Lint all commits from a branch
+
+```shell
+podman run -it --rm -v $PWD:/data ghcr.io/voxpupuli/commitlint:latest \
+  --from $(git merge-base $(git symbolic-ref refs/remotes/origin/HEAD --short) HEAD) \
+  --to HEAD
+```
+
+### More options
+
+For more options see:
+
+```shell
+podman run -it --rm -v $PWD:/data ghcr.io/voxpupuli/commitlint:latest --help
+```
+
+### Example commitlint config
+
+See [.commitlint.yaml](.commitlintrc.yaml)
+
+```yaml
+---
+# The rules below have been manually copied from @commitlint/config-conventional
+# and match the v1.0.0 specification:
+# https://www.conventionalcommits.org/en/v1.0.0/#specification
+#
+# You can remove them and uncomment the config below when the following issue is
+# fixed: https://github.com/conventional-changelog/commitlint/issues/613
+#
+# extends:
+#   - '@commitlint/config-conventional'
+rules:
+  body-leading-blank: [1, always]
+  body-max-line-length: [2, always, 100]
+  footer-leading-blank: [1, always]
+  footer-max-line-length: [2, always, 100]
+  header-max-length: [2, always, 100]
+  subject-case:
+    - 2
+    - never
+    - [sentence-case, start-case, pascal-case, upper-case]
+  subject-empty: [2, never]
+  subject-full-stop: [2, never, "."]
+  type-case: [2, always, lower-case]
+  type-empty: [2, never]
+  type-enum:
+    - 2
+    - always
+    - [build, chore, ci, docs, feat, fix, perf, refactor, revert, style, test]
+```