Document approach to Bootstrap 5 form rendering

docs/forms.rst

@@ -30,4 +30,19 @@ See below for an example.
         <div class="valid-feedback">Looks good!</div> <!-- validation text -->
     </div>
 
-How and in which order these will components be rendered differs per widget type.
+How and in which order these will components be rendered differs per widget type.
+
+1. We must support `bootstrap_formset`, `bootstrap_form`, and `bootstrap_field` to render a sensible default layout for the above components.
+2. We should offer support to easily set or override the classes for the wrapper.
+3. We could offert the option to override the templates used to generate this output.
+
+Input groups for more complex fields
+------------------------------------
+
+Reference: https://getbootstrap.com/docs/5.0/forms/input-group/
+
+Bootstrap 5 offers Input groups to combine fields and add-ons (both before and after the field).
+
+1. We must support separate rendering of labels, fields, help texts and errors so that users can build their own input groups.
+2. We should offer support for add-ons (before and after) as part of `bootstrap_field`.
+3. We could add support in form, field or widget definition to define add-ons in Python code.