Add Lightweight Metrics Collection Using DeveloperMetrics GitHub Action

[yunks128]

Purpose

Introduce a simplified approach for collecting DORA metrics in single-repository projects using GitHub Actions.

Proposed Changes

• [ADD] Section on DeveloperMetrics GitHub Action as an alternative to DevLake
• [ADD] Quick start example YAML for easy integration
• [UPDATE] Clarified use cases and tool selection guidance based on project complexity

Issues

• Related to [issue-160](https://github.com/NASA-AMMOS/slim/issues/160)

Testing

• Verified markdown rendering locally

[riverma]

I think I'll take a pass at this as well - to potentially deprecate Apache DevLake in the guide.

[riverma]

@yunks128 - I think let's do a couple things before considering a merge:

• (@yunks128) Move the workflow action to '/assets'
• (@yunks128) Show examples of the GH metrics badges so people know what it looks like
• (@yunks128) Explain how the badge works / gets updated
• (@riverma) Deprecate Apache DevLake content (if we do deprecate, we should be clear about the versioned released o the SLIM website)

[sonarqubecloud[bot]]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[sonarqubecloud[bot]]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[yunks128]

@riverma I took another pass and resolved the conflict in registry.json. It should be all set for your review now—thanks!