Make more coherent README.md note.

Author: ayjayt

src/py/tests/README.md

@@ -1,3 +1,6 @@
+
+To clarify three similar test files:
+
 - test_public_api.py does render tests of renderers in __init__.py
   - it does not parametrize
 - test_init.py tests that wrappers are proper and pass args/kwargs
@@ -7,5 +10,5 @@
 
 
 
-Parameterizing actual renders would be a huge burden, but integration tests
-with mocks test it more completely
+Parameterizing actual renders would be a huge burden, so integration tests
+with mocks are currently the most complete tests.