more details on pyenv vs matplotlib

hugo/content/installation/py/linux.md

@@ -13,13 +13,22 @@ cause inconsistencies and break the system. Therefore, distributions at
 some point (e.g. Debian 12) disabled Pip, which terminates with
 `error: externally-managed-environment`. While this behavior can be
 overridden by a special flag, we advise against.
-
-#### Python in pyenv
-
 Rather, we recommend escaping from Python version hell by using the
 Python version manager [pyenv](https://github.com/pyenv/pyenv).
 
-Install the venerable GUI toolkit Tk (e.g. Debian package tk-dev).
+#### Requirements
+
+To provide a backend for the Python plotting module matplotlib,
+install the GUI toolkit Tk before installing pyenv (otherwise,
+you will need to rerun `pyenv install <version>`).
+
+| Distribution | Package  |
+| ------------ | -------  |
+| Debian       | tk-dev   |
+| Redhat       | tk-devel |
+| Archlinux    | Tk       |
+
+#### Python in pyenv
 
 Prepare the shell by adding
 ```