docs: fix how to contribute link

[CDiezRodriguez]

Description

Fix the "How to Contribute" link.

Why

The existing link is broken.

Issue

Issue #483

Checklist

Please delete options that are not relevant.

• [X] I have followed the contributing guidelines
• [X] I have successfully tested my changes locally

[sonarcloud[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