BS5 Theme

docs/development/custom/custom-themes.md

@@ -0,0 +1,19 @@
+# Theme Hooks
+
+The theme hook allows custom themes to be loaded dynamically by AAs CSS/JS Bundles, as selected by Users.
+
+To register a ThemeHook class you would do the following:
+
+```Python
+@hooks.register('theme_hook')
+def register_darkly_hook():
+    return ThemeHook()
+```
+
+The `ThemeHook` class specifies some parameters/instance variables required.
+
+```eval_rst
+.. autoclass:: allianceauth.theme.hooks.ThemeHook
+    :members: __init__
+    :undoc-members:
+```