Add 3 icons and fix wrong redirect in contribution guide

[bl4zee1g]

I updated a link in the contribution guide that redirected to issues tagged enhancement instead of icon, added 2 icons of services that i personally use (and meet the requirements) and added the deepl icon as requested in https://github.com/stratumauth/app/issues/1349

[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