Being able to add a custom link to Jellyfin side bar/tab

Hello, for the context : I wanted to add an "Ombi" custom link to Jellyfin using 'config.json' in /usr/share/jellyfin/web to be able to search with Ombi directly from Jellyfin, but we don't have access to this path

Here's the link that explains how to add custom link on Jellyfin : https://github.com/BobHasNoSoul/jellyfin-mods#add-custom-link-to-side-bar

I didn't find another way to do it for now