[3.4] Split documents per OS, fix few things, drop and add few OSes (#5328) (#5331)

* 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'
(cherry picked from commit cbbb9d9b9b)

Co-authored-by: jack1142 <6032823+jack1142@users.noreply.github.com>

Co-authored-by: jack1142 <6032823+jack1142@users.noreply.github.com>

docs/install_guides/_includes/install-python-pyenv.rst

@@ -0,0 +1,34 @@
+----------------------------
+Installing Python with pyenv
+----------------------------
+
+On distributions where Python 3.9 needs to be compiled from source, we recommend the use of pyenv.
+This simplifies the compilation process and has the added bonus of simplifying setting up Red in a
+virtual environment.
+
+.. prompt:: bash
+
+    command -v pyenv && pyenv update || curl https://pyenv.run | bash
+
+**After this command, you may see a warning about 'pyenv' not being in the load path. Follow the
+instructions given to fix that, then close and reopen your shell.**
+
+Then run the following command:
+
+.. prompt:: bash
+
+    CONFIGURE_OPTS=--enable-optimizations pyenv install 3.9.7 -v
+
+This may take a long time to complete, depending on your hardware. For some machines (such as
+Raspberry Pis and micro-tier VPSes), it may take over an hour; in this case, you may wish to remove
+the ``CONFIGURE_OPTS=--enable-optimizations`` part from the front of the command, which will
+drastically reduce the install time. However, be aware that this will make Python run about 10%
+slower.
+
+After that is finished, run:
+
+.. prompt:: bash
+
+    pyenv global 3.9.7
+
+Pyenv is now installed and your system should be configured to run Python 3.9.