[changlog] Mention MPNC change

CHANGELOG.md

@@ -12,6 +12,27 @@ Differences Between DuMu<sup>x</sup> 3.4 and DuMu<sup>x</sup> 3.3
     - `extractmodulepart.sh` no longer creates an install file, instead, you can now generate install scripts for your module using the new script `bin/util/makeinstallscript.py`.
     - Note: the old shells script will be removed after release 3.4.
 
+### Immediate interface changes not allowing/requiring a deprecation period:
+- __MPNC__: The `MPAdapter` can now also be called with a temporary `pcKrSw` objects. For this, the compiler needs to deduce the
+            class's template argument types. You may need to adapt your `spatialParams` from
+
+```
+using MPAdapter = Dumux::FluidMatrix::MPAdapter<PcKrSwCurve, 2>;
+...
+auto fluidMatrixInteractionAtPos(const GlobalPosition &globalPos) const
+{
+    return makeFluidMatrixInteraction(MPAdapter(pcKrSwCurve_));
+}
+```
+to
+```
+// alias for MPAdapter is removed
+auto fluidMatrixInteractionAtPos(const GlobalPosition &globalPos) const
+{
+    return makeFluidMatrixInteraction(FluidMatrix::MPAdapter(pcKrSwCurve_));
+}
+```
+
 Differences Between DuMu<sup>x</sup> 3.3 and DuMu<sup>x</sup> 3.2
 =============================================