[Docs] Fix pip advice in install docs

docs/admin/10_install.rst

@@ -50,6 +50,7 @@ Install some packages from the Debian package system.
                nginx-full \
                python3 \
                python3-dev \
+               python3-pip \
                libpq-dev \
                yarnpkg \
                python3-virtualenv \
@@ -144,7 +145,7 @@ You only need to install these additional dependencies if installing the meta-pa
 After that, you can install the aleksis meta-package, or only `aleksis-core`:
 
 .. code-block:: shell
-   pip3 install aleksis
+   pip3 install --break-system-packages aleksis
    aleksis-admin vite build
    aleksis-admin collectstatic
    aleksis-admin migrate