Adjust comment

src/sage/rings/number_field/number_field_rel.py

@@ -1359,9 +1359,9 @@ def free_module(self, base=None, basis=None, map=True):
 
         - ``base`` -- a subfield
 
-        - ``basis`` -- a list of elements giving a basis over the subfield (optional)
+        - ``basis`` -- (optional) a list of elements giving a basis over the subfield
 
-        - ``map`` -- whether to return isomorphisms to and from the vector space (default ``True``)
+        - ``map`` -- (default ``True``) whether to return isomorphisms to and from the vector space
 
         EXAMPLES::
 

src/sage/rings/padics/padic_extension_generic.py

@@ -650,10 +650,14 @@ def free_module(self, base=None, basis=None, map=True):
 
 # We could have used morphisms in the category
 # FiniteDimensionalModulesWithBasis over Qp(p)
-# But this would require making p-adic fields
-# part of this category which has a lot of side
-# effects (adding methods which will show up
-# in tab completion for example).  For now we
+# But currently if you try to add this category
+# to p-adic extensions you get errors on
+# object creation.  Moreover, some of the methods
+# obtained from the category (such as dimension)
+# don't take base ring into account, making it
+# awkward to treat the same field as simultaneously
+# an object in two free module categories with
+# different base rings. So for now we
 # just stick with Map.
 class pAdicModuleIsomorphism(Map):
     r"""