Minor tweaks to new Requires-Python guide

- clarify minimum version requirement is for setuptools
- minor markup fixes

Author: ncoghlan

source/guides/dropping-older-python-versions.rst

@@ -28,13 +28,13 @@ Defining the Python version required
 1. Download the newest version of Setuptools
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-Ensure that before you generate source distributions or binary distributions, you update Setuptools and twine.
+Ensure that before you generate source distributions or binary distributions, you update Setuptools and install twine.
 
 Steps::
 
    pip install --upgrade setuptools twine
 
-Version should be above 24.0.0.
+`setuptools` version should be above 24.0.0.
 
 2. Specify the version ranges for supported Python distributions
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -49,7 +49,7 @@ Examples::
 The way to set those values is within the call to `setup` within your setup.py script. This will insert the Requires-Python
 metadata values based on the argument you provide in `python_requires`.
 
-..code-block:: Python
+.. code-block:: python
 
     from setuptools import setup
 
@@ -67,7 +67,7 @@ Within a Python source package (the zip or the tar-gz file you download) is a te
 This file is generated by Distutils or :ref:`setuptools` when it generates the source package. 
 The file contains a set of keys and values, the list of keys is part of the PyPa standard metadata format. 
 
-You can see the contents of the generated file like this:
+You can see the contents of the generated file like this::
 
     tar xvfz dist/my-package-1.0.0.tar.gz -O | cat */PKG-INFO
 
@@ -93,4 +93,4 @@ It must be done in this order for the automated fail-back to work.
 For example, you published the Requires-Python: ">=2.7" as version 1.0.0 of your package.
 
 If you were then to update the version string to ">=3.5", and publish a new version 2.0.0 of your package, any users running Pip 9.0+ from version 2.7 will
-have version 1.0.0 of the package installed, and any >=3.5 users will receive version 2.0.0.
+have version 1.0.0 of the package installed, and any >=3.5 users will receive version 2.0.0.