[FIX] util/records: fix delete_unused DOCSTRING

`delete_unused`, in spite of its name, deletes records even if they are used,
provided they are not part of a foreign key with `restrict` or `set` ondelete
clause (iow: allowing for cascading foreign keys).

Author: Pirols

Diff for: src/util/records.py

@@ -1098,14 +1098,17 @@ def add_ref(ref):
 
 def delete_unused(cr, *xmlids, **kwargs):
     """
-    Remove unused records.
+    Remove unrestricted records.
 
-    This function will remove records pointed by `xmlids` only if they are not referenced
-    from any table.
+    This function will remove records, pointed by `xmlids`, only if they are NOT referenced
+    from any table with `restrict` or `set` ondelete clauses.
 
     .. note::
        The records that cannot be removed are set as `noupdate=True`.
 
+    .. warning::
+       Indirect references are not checked and can cause the util to fail.
+
     :param list(str) xmlids: list of xml_ids to check for removal
     :param bool deactivate: whether to deactivate records that cannot be removed because
                             they are referenced, `False` by default