chore: add new fields from PEP 794

Signed-off-by: Henry Schreiner <henryfs@princeton.edu>

Author: henryiii

peps/pep-0808.rst

@@ -124,6 +124,7 @@ cases that have come up:
   field specifically because you _want_ the build tool to add these, so the
   ``[project]`` table setting would be useless, you'd almost never be able to
   use it.
+- Adding generated modules to ``import-names`` or ``import-namespaces``.
 
 All of these use cases have a similar feature: they are adding something
 dynamically to a fixed list (possibly a narrower pin for the dependency case).
@@ -231,6 +232,8 @@ The fields that are arrays or tables with arbitrary entries are:
 * ``optional-dependencies``: A new extra or new items can be added to a
   existing extra.
 * ``urls``: New urls can be added. Existing ones cannot be changed or removed.
+* ``import-names``, ``import-namespaces``: New import names or namespaces can
+  be added. Existing ones cannot be modified or removed.
 
 To add items, users must opt-in by listing the field in ``dynamic``; without
 that, the metadata continues to be entirely static.