Release Notes:
- Updated the Linux manual installation docs to fix windows not matching
with desktop icons
([#14435](https://github.com/zed-industries/zed/issues/14435)).
The automated `curl | bash` installation script already renames the
`zed.desktop` file to match the window, so most users will not be facing
this issue. This is only affecting users who have downloaded and
extracted the files following the manual instructions.
Since the app ID and the desktop file name are not the same, open
windows are not being matched with the desktop icons, therefore showing
a default one. This PR changes the documentation to tell users they
should rename the `.desktop` file to `dev.zed.Zed.desktop`, and
therefore match the automated install script.
Before:

After:

Hello, I'm one of the maintainers of the Zed package on Terra. I made
the following changes:
- Mention the Terra stable package, instead of only preview and nightly.
- Link to sources for Terra packages instead of pkgs.org.
- Mention Ultramarine in addition to Fedora (one of Terra's targets).
Release Notes:
- N/A