Merge pull request cli#12191 from cli/af/12182-debian-ubuntu-community-install-docs

Add Debian/Ubuntu to unofficial packages

Author: andyfeller

docs/install_linux.md

@@ -207,6 +207,13 @@ To upgrade:
 conda update gh --channel conda-forge
 ```
 
+### Debian Community
+
+The [GitHub CLI package](https://packages.debian.org/bookworm/gh) is supported by the Debian community with updates powered by [Debian Go Packaging Team](https://salsa.debian.org/go-team/packages/gh).
+
+> [!NOTE]
+> As of November 2025, GitHub CLI maintainers strongly recommend [official Debian packages](#debian) especially as the community-distributed `2.45.x` / `2.46.x` version is broken due to deprecated GitHub APIs.
+
 ### Fedora Community
 
 The [GitHub CLI package](https://packages.fedoraproject.org/pkgs/gh/gh/) is supported by the Fedora community with updates powered by [Fedora Project](https://src.fedoraproject.org/rpms/gh).
@@ -389,6 +396,13 @@ To upgrade:
 spack uninstall gh && spack install gh
 ```
 
+### Ubuntu Community
+
+The [GitHub CLI package](https://packages.ubuntu.com/noble/gh) is synced from [upstream Debian Community package](#debian-community).
+
+> [!NOTE]
+> As of November 2025, GitHub CLI maintainers strongly recommend [official Debian packages](#debian) especially as the community-distributed `2.45.x` / `2.46.x` version is broken due to deprecated GitHub APIs.
+
 ### Void Linux
 
 The [GitHub CLI package](https://voidlinux.org/packages/?arch=x86_64&q=github-cli): is supported by the Void Linux community with updates powered by [void-linux/void-packages](https://github.com/void-linux/void-packages/tree/master/srcpkgs/github-cli).