Add links to all issues in the 2.4.0 section of the changelog

Description

This PR adds links to all issues in the 2.4.0 sectios of the changelog.

[ ] Bug fix (non-breaking change which fixes an issue)
[ ] New feature (non-breaking change which adds functionality)
[ ] Breaking change (fix or feature that would cause existing functionality to change)
- [ ] This change is only breaking for integrators, not for external standards or end-users.
[x] Documentation improvement

[x] I have checked there is no other PR open for the same change.
[x] I have read the Contribution Guidelines.
[x] I grant the project the right to include and distribute the code under the BSD-3-Clause license (and I have the right to grant these rights).
[ ] I have added tests to cover my changes.
[ ] I have verified that the code complies with the projects coding standards.
[ ] [Required for new sniffs] I have added XML documentation for the sniff.