Update dsmr.markdown to add Kaifa MA304C (home-assistant#28469)

I have a working instance with the Kaifa MA304C using DSMR version 4.2

Author: TheLizard

source/_integrations/dsmr.markdown

@@ -58,6 +58,7 @@ This integration is known to work for:
 - Landis+Gyr E350 (DMSR 4)
 - Landis+Gyr ZCF110 / ZM F110 (DSMR 4.2)
 - Kaifa E0026
+- Kaifa MA304C (DSMR 4.2)
 - Kamstrup 382JxC (DSMR 2.2)
 - Sagemcom XS210 ESMR5
 - Sagemcom T211