docs: Add section about distro package installation (#3208)

* add section about distibution packages

* highlight

docs/setup.md

@@ -20,10 +20,9 @@ Install via the Nix package manager (Linux/macOS)
 ```{.bash .copy}
 nix shell github:pwndbg/pwndbg
 ```
-### Through package manager
+### Official Pwndbg packages
 When installing with GDB, you may also download a package to install through your package manager of choice. Download the package from the [releases page](https://github.com/pwndbg/pwndbg/releases) and pick the appropriate download from the second table.
 
-
 RPM-based Systems (CentOS/Alma/Rocky/RHEL):
 ```{.bash .copy}
 dnf install ./pwndbg-2025.05.30.x86_64.rpm
@@ -40,6 +39,29 @@ Arch Linux:
 ```{.bash .copy}
 pacman -U ./pwndbg-2025.05.30-1-x86_64.pkg.tar.zst
 ```
+### Distro packages
+You may want to install Pwndbg through your distribution's package manager. This installation method is **not officially supported** because we cannot control the versions of the python dependencies Pwndbg uses in this case. Please use any other installation method when reproducing bug reports (portable package is probably simplest in this case). If a bug reproduces with a distro package but not with any of the supported installation methods, please report it to the package maintainer; if the problem cannot be fixed, let us know and we will add it to the list of known issues below.
+
+=== "Arch"
+    ```{.bash .copy}
+    sudo pacman -S pwndbg
+    ```
+    You will also need to source Pwndbg from your `~/.gdbinit`. Add this line to the beginning of that file:
+    ```{.bash .copy}
+    source /usr/share/pwndbg/gdbinit.py
+    ```
+    Pwndbg will be started every time you invoke `gdb` now.
+
+=== "Gentoo"
+    ```{.bash .copy}
+    sudo emerge --ask dev-debug/pwndbg
+    ```
+
+----
+
+Known issues:
+
++ We require `gnureadline` rather than Arch's `pyreadline3`. This causes tab completion to not work.
 
 ## Installing pwndbg-lldb
 These installation methods provide the