docs: update supported versions

Author: jaredhendrickson13

docs/INSTALL_AND_CONFIG.md

@@ -21,6 +21,7 @@ run pfSense. It's recommended to follow Netgate's [minimum hardware requirements
 - pfSense Plus 25.07.1
 - pfSense Plus 25.11
 - pfSense Plus 25.11.1
+- pfSense Plus 26.03
 
 !!! Warning
     Installation of the package on unsupported versions of pfSense may result in unexpected behavior and/or system instability.