Start fleshing out the docs more - rearrange, separate out modules section, move files over to md (from rst)

docs/source/core_modules.rst

@@ -0,0 +1,11 @@
+Core Modules
+============
+
+These pages are intended for developers of the `auto-archiver` package, and include documentation on the core classes and functions used by the auto-archiver
+
+.. toctree::
+   :titlesonly:
+
+   {% for page in pages|selectattr("is_top_level_object") %}
+   {{ page.include_path }}
+   {% endfor %}