fix: Release note creation (open-component-model#1893)

<!-- markdownlint-disable MD041 -->
#### What this PR does / why we need it

1. Release note header is not correctly replaced because the regex
assumed the line would start with `[` but it actually starts with `##
[`. The changed implementation now checks for a line starting with `##
[cli/` and will only replace it on the first line. This should work as
long no one wants to break this by intend. However, the PR title checker
should prevent this.

2. Added a quick installation and usage guide for the ocm cli. The
script cannot be used yet because we need to finish the
[implementation](https://github.com/open-component-model/ocm-website/pull/738/changes).

#### Which issue(s) this PR fixes

Fixes open-component-model/ocm-project#923

#### Testing

- Tested release notes title replacement locally by using

```js
const fs = require('fs');

const finalTag = "cli/v0.1.0";
const rcTag = "cli/v0.1.0-rc.1";
const notesFile = "notes.md";

let notes = fs.existsSync(notesFile)
    ? fs.readFileSync(notesFile, 'utf8').trim()
    : `Promoted from ${rcTag}`;

// Replace RC header with final release header by replacing the whole line
// From: "[cli/v0.17.0-rc.1] - 2026-02-02"
// To:   "[cli/v0.17.0] - promoted from [cli/v0.17.0-rc.1] on 2026-02-16"
// Assumption: There is only one line starting with "## [cli/" in the notes file, which is the RC header.
// If there are multiple, this will only replace the first one.
const today = new Date().toISOString().split('T')[0];
notes = notes.replace(
    /^## \[cli\/.*/,
    `## [${finalTag}] - promoted from [${rcTag}] on ${today}`
);

console.log(notes);
```

and the release notes from
[`0.1.0-rc.1`](https://github.com/open-component-model/open-component-model/releases/tag/cli%2Fv0.1.0-rc.1)
in the respective file:

```bash
$> node test-release-notes.js | head -n 20
## [cli/v0.1.0] - promoted from [cli/v0.1.0-rc.1] on 2026-03-04

### 🚀 Features

- Migrate configuration v1 (#35)
...
```

- Testing release notes creation with `git-cliff`

  - Install `git-cliff` using `brew install git-cliff`
  - Run

```bash
$> git-cliff \
  --config cli/cliff.toml \
  --include-path "cli/**" \
  --tag-pattern "^cli/v\\d+\\.\\d+\\.\\d+(?:[-\\w\\.]+)?$" \
  --ignore-tags "^cli/v\\d+\\.\\d+\\.\\d+-rc\\.\\d+$" \
  --tag "cli/v0.1.0" \
  -o "CHANGELOG.md" \
  --use-branch-tags \
  --latest
```

- Check `./CHANGELOG.md` (using a picture here because md-formatting in
md-formatting cannot be properly processed by GitHub)
<img width="776" height="312" alt="image"
src="https://github.com/user-attachments/assets/4f4d58a3-64fa-4149-8472-bc626c5dd403"
/>


  

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

* **Documentation**
* Added a quick installation and usage guide with curl and Docker
commands to the changelog.

* **Chores**
* Improved release notes header handling for final releases: stricter
header validation, early failure when the expected header is missing,
and replacement of the RC header line with the final header (including
tag and promotion date); clarified inline comments.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

---------

Signed-off-by: Frederic Wilhelm <frederic.wilhelm@sap.com>

Author: frewilhelm

.github/workflows/cli-release.yml

@@ -375,13 +375,19 @@ jobs:
               ? fs.readFileSync(notesFile, 'utf8').trim()
               : `Promoted from ${rcTag}`;
 
-            // Replace RC header with final release header
+            // Replace RC header with final release header by replacing the whole line
             // From: "[cli/v0.17.0-rc.1] - 2026-02-02"
             // To:   "[cli/v0.17.0] - promoted from [cli/v0.17.0-rc.1] on 2026-02-16"
             const today = new Date().toISOString().split('T')[0];
+            // Regex to match the RC header line, ensuring it starts with "## [cli/v" and contains "-rc."
+            const rcHeaderPattern = /^## \[cli\/v\d+\.\d+\.\d+-rc\.\d+\].*$/m;
+            if (!rcHeaderPattern.test(notes)) {
+              core.setFailed(`RC header not found in release notes for ${rcTag}`);
+              return;
+            }
             notes = notes.replace(
-              /^\[([^\]]+)\]\s*-\s*[\d-]+/,
-              `[${finalTag}] - promoted from [${rcTag}] on ${today}`
+              rcHeaderPattern,
+              `## [${finalTag}] - promoted from [${rcTag}] on ${today}`
             );
 
             // Use make_latest to control whether this release is marked as "latest"

cli/cliff.toml

@@ -19,6 +19,26 @@ body = """
             {{ commit.message | upper_first }}\
     {% endfor %}
 {% endfor %}
+
+### Quick installation and usage guide
+
+To install the latest version of OCM, you can use the following command:
+
+```bash
+curl -fsSL https://ocm.software/install-cli.sh | sudo bash
+```
+
+(For more installation options, check out our [installation guide](https://ocm.software/dev/docs/getting-started/install-the-ocm-cli/).)
+
+You can also use our container to run OCM without installing it:
+
+```bash
+docker run -t ghcr.io/open-component-model/cli:latest --help
+```
+
+Check out our [guide](https://ocm.software/dev/docs/how-to/how-to-use-the-ocm-cli-container-image/) on how to use the
+OCM CLI container image for more details.
+
 {% if github.contributors | length > 0 %}
 ### Community & Contributors