pyoxy: add installing docs

Author: indygreg

pyoxy/docs/pyoxy.rst

@@ -16,5 +16,6 @@ PyOxidizer project, leveraging much of its *technology*.
    :maxdepth: 2
 
    pyoxy_overview
+   pyoxy_installing
    pyoxy_yaml
    pyoxy_developing

pyoxy/docs/pyoxy_installing.rst

@@ -0,0 +1,40 @@
+.. _pyoxy_installing:
+
+==========
+Installing
+==========
+
+It is **highly recommended** to obtain and use one of the official pre-built
+binaries for PyOxy. These can be obtained from GitHub releases. Go to
+https://github.com/indygreg/PyOxidizer/releases and scroll until you find
+the latest release for PyOxy.
+
+System Requirements
+===================
+
+The requirements in this section only apply to the official pre-built
+binaries. Binaries built by others may not have the same requirements.
+
+Linux
+-----
+
+The x86_64-unknown-linux-gnu binaries should work on any Linux having
+glibc 2.18+ and GCC 4.2+ and conform to the Linux Standard Base Core
+Specification. This should be ~every Linux distribution released since
+2014-2015.
+
+.. note::
+
+   Modern versions of Fedora / CentOS / RHEL have a bug and
+   `don't conform to the LSB Core Specification <https://bugzilla.redhat.com/show_bug.cgi?id=2055953>`_
+   unless you install the ``libxcrypt-compat`` package. If you see
+   an error about missing ``libcrypt.so.1``, your distribution is buggy.
+
+macOS
+-----
+
+The x86_64-apple-darwin binaries target macOS 10.9+.
+
+The aarch64-apple-darwin binaries target macOS 11.0+.
+
+The binaries should work on a fresh install of macOS.