Update docs/src/v14_migration_guide.md

Co-authored-by: Sam Isaacson <[email protected]>

Author: TorkelE

docs/src/v14_migration_guide.md

@@ -185,7 +185,7 @@ This might generate a silent error, where the remade problem is different from t
 This bug was likely present on earlier versions as well, but was only recently discovered. While we hope it will be fixed soon, the issue is in ModelingToolkit, and will not be fixed until its maintainers find the time to do so.
 
 #### Depending on parameter order is even more dangerous than before
-In early versions of Catalyst, parameters and species were provided as vectors (e.g. `[1.0, 2.0]`) rather than maps (e.g. `[p => 1.0, d => 2.0]`). While we have already *strongly* recommended users to use the map form (or they might produce unintended results), the vector form is still (technically). Due to recent internal ModelingToolkit updates, the risk of unexpected behaviour when providing parameter values as vectors is even larger than before.
+In early versions of Catalyst, parameters and species were provided as vectors (e.g. `[1.0, 2.0]`) rather than maps (e.g. `[p => 1.0, d => 2.0]`). While we previously *strongly* recommended users to use the map form (or they might produce unintended results), the vector form was still supported (technically). Due to recent internal ModelingToolkit updates, the purely numeric form is no longer supported and should never be used -- it will potentially lead to incorrect values for parameters and/or initial conditions. Note that if `rn` is a complete `ReactionSystem` you can now specify such mappings via `[rn.p => 1.0, rn.d => 2.0]`.
 
 *Users should never use vector-forms to represent parameter and species values*