docs: fix States.from_enum() bugfix description in release notes

The bug was a silent failure (states not collected), not an error.

Author: fgmacedo

docs/releases/3.1.0.md

@@ -176,7 +176,7 @@ machine instance concurrently. This is now documented in the
   [#596](https://github.com/fgmacedo/python-statemachine/pull/596).
 
 - `States.from_enum()` now works correctly inside compound and parallel states. Previously
-  it raised an error when used as a nested state declaration.
+  the states were silently not collected when used as a nested state declaration.
   [#607](https://github.com/fgmacedo/python-statemachine/pull/607),
   fixes [#606](https://github.com/fgmacedo/python-statemachine/issues/606).