Fix installation instructions for Pop! OS

(System76 OS)

More secure command as well that's more clear about what it actually does.

[fix typo] Fourth, not third, command.

content/downloads/_index.md

@@ -90,10 +90,11 @@ docker run -d -v /srv/jellyfin/config:/config -v /srv/jellyfin/cache:/cache -v /
         <div id="deb_repo_stable" style="display:none;">
             <pre><code>sudo apt install curl gnupg
 curl -fsSL https://repo.jellyfin.org/ubuntu/jellyfin_team.gpg.key | sudo gpg --dearmor -o /etc/apt/trusted.gpg.d/jellyfin.gpg
-echo "deb [arch=$( dpkg --print-architecture )] https://repo.jellyfin.org/$( awk -F'=' '/^ID=/{ print $NF }' /etc/os-release ) $( awk -F'=' '/^VERSION_CODENAME=/{ print $NF }' /etc/os-release ) main" | sudo tee /etc/apt/sources.list.d/jellyfin.list
+RELEASE=$( hash pop-upgrade 2> /dev/null && echo Ubuntu || lsb_release --id --short )
+echo "deb [arch=$( dpkg --print-architecture )] https://repo.jellyfin.org/"${RELEASE,,}" $( lsb_release --codename --short ) main" | sudo tee /etc/apt/sources.list.d/jellyfin.list
 sudo apt update
 sudo apt install jellyfin</code></pre>
-        <p><i>Note:</i> The third command should give you output similar to <code>deb [arch=(architecture)] https://repo.jellyfin.org/(distribution) (release) main"</code>. We support <code>amd64</code>, <code>armhf</code>, and <code>arm64</code> for architectures, <code>debian</code> and <code>ubuntu</code> for distributions, <code>buster</code> and <code>bullseye</code> for Debian releases and <code>bionic</code>, <code>focal</code>, <code>impish</code> and <code>jammy</code> for Ubuntu releases. If you see something different in your output, you might need to manually modify it. Use the closest equivalent Debian or Ubuntu version instead.</p>
+        <p><i>Note:</i> The fourth command should give you output similar to <code>deb [arch=(architecture)] https://repo.jellyfin.org/(distribution) (release) main"</code>. We support <code>amd64</code>, <code>armhf</code>, and <code>arm64</code> for architectures, <code>debian</code> and <code>ubuntu</code> for distributions, <code>buster</code> and <code>bullseye</code> for Debian releases and <code>bionic</code>, <code>focal</code>, <code>impish</code> and <code>jammy</code> for Ubuntu releases. If you see something different in your output, you might need to manually modify it. Use the closest equivalent Debian or Ubuntu version instead.</p>
         <p>Once installed, Jellyfin will be running as a service. Manage it with <pre><code>sudo systemctl {action} jellyfin.service</code></pre> or <pre><code>sudo service jellyfin {action}</code></pre></p>
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         <div id="deb_repo_nightly" style="display:none;">