Split documents per OS, fix few things, drop and add few OSes (#5328)

* Exclude include files from being built

* Split install guides into multiple documents (one per OS/version combo)

* Update references

* Unify anchor names

* Update pyenv requirements in CentOS 7 guide

* Update install guides for RHEL derivatives to not use pyenv

* Add guide for Rocky Linux 8

* 8.4+ -> 8.4-8.x

* Add 'the'

docs/install_guides/_includes/create-env-with-venv.rst

@@ -0,0 +1,38 @@
+------------------------------
+Creating a Virtual Environment
+------------------------------
+
+.. tip::
+
+    If you want to learn more about virtual environments, see page: `about-venvs`
+
+We require installing Red into a virtual environment. Don't be scared, it's very
+straightforward.
+
+**************
+Using ``venv``
+**************
+
+This is the quickest way to get your virtual environment up and running, as `venv` is shipped with
+python.
+
+First, choose a directory where you would like to create your virtual environment. It's a good idea
+to keep it in a location which is easy to type out the path to. From now, we'll call it
+``redenv`` and it will be located in your home directory.
+
+Create your virtual environment with the following command:
+
+.. prompt:: bash
+
+    python3.9 -m venv ~/redenv
+
+And activate it with the following command:
+
+.. prompt:: bash
+
+    source ~/redenv/bin/activate
+
+.. important::
+
+    You must activate the virtual environment with the above command every time you open a new
+    shell to run, install or update Red.