PEP 665: spell out that if the PEP doesn't say something then you can do what you want

pep-0665.rst

@@ -233,6 +233,19 @@ to benefit installers. It also means the complexity of package
 dependencies is simpler and easier to comprehend to avoid ambiguity.
 
 
+-----------------------
+As Flexible as Possible
+-----------------------
+
+Realizing that workflows vary greatly between companies, projects, and
+even people, this PEP tries to be strict where it's important and
+undefined/flexible everywhere else. As such, this PEP is strict where
+it is important for reproducibility and compatibilitiy, but does not
+specify any restrictions in other situations not covered by this PEP;
+if the PEP does not specifically state something then it is assumed to
+be up to the locker or installer to decide what is best.
+
+
 =============
 Specification
 =============