Update linux.md to add Ubuntu community packages (#49654)

Today I added ubuntu LTS distributions to my debian repo.
You can find the index of noble and jammy here
https://debian.griffo.io/apt/dists/noble/main/binary-amd64/Packages
https://debian.griffo.io/apt/dists/jammy/main/binary-amd64/Packages

So far zed is the second most download package in my repo!

<img width="769" height="648" alt="image"
src="https://github.com/user-attachments/assets/e07a2312-e56a-4e2c-86d9-70cbf6c6aa73"
/>

Release Notes:

- N/A

docs/src/linux.md

@@ -65,7 +65,7 @@ We'd love your help making Zed available for everyone. If Zed is not yet availab
 
 The packages in this section provide binary installs for Zed but are not official packages within the associated distributions. These packages are maintained by community members and as such a higher level of caution should be taken when installing them.
 
-#### Debian
+#### Debian and Ubuntu
 
 Zed is available in [this community-maintained repository](https://debian.griffo.io/).