DOC: Fix minimum Python version in contributing docs (pandas-dev#40552)

* DOC: Fix minimum Python version in contributing docs

* DOC: Fix minimum Python version in contributing environment docs

Author: hasan-yaman

doc/source/development/contributing_environment.rst

@@ -189,7 +189,7 @@ Creating a Python environment (pip)
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 If you aren't using conda for your development environment, follow these instructions.
-You'll need to have at least Python 3.7.0 installed on your system. If your Python version
+You'll need to have at least the :ref:`minimum Python version <install.version>` that pandas supports. If your Python version
 is 3.8.0 (or later), you might need to update your ``setuptools`` to version 42.0.0 (or later)
 in your development environment before installing the build dependencies::
 

doc/source/getting_started/install.rst

@@ -15,6 +15,8 @@ Instructions for installing from source,
 `PyPI <https://pypi.org/project/pandas>`__, `ActivePython <https://www.activestate.com/activepython/downloads>`__, various Linux distributions, or a
 `development version <https://github.com/pandas-dev/pandas>`__ are also provided.
 
+.. _install.version:
+
 Python version support
 ----------------------