Fix ambiguous antecedent

Author: kgryte

spec/assumptions.md

@@ -69,6 +69,6 @@ interactive user experience. However, in case existing libraries differ in
 behavior, the more strict version of that behavior is typically preferred. A
 good example is array inputs to functions - while NumPy accepts lists, tuples,
 generators, and anything else that could be turned into an array, most other
-libraries only accept their own array types. This standard follows that choice.
+libraries only accept their own array types. This standard follows the latter choice.
 It is likely always possible to put a thin "interactive use convenience layer"
 on top of a more strict behavior.