Fix leveling "Point n of 3" message (#18639)

Marlin/src/gcode/bedlevel/abl/G29.cpp

       // Probe at 3 arbitrary points
 
       LOOP_L_N(i, 3) {
-        if (verbose_level) SERIAL_ECHOLNPAIR("Probing point ", int(i), "/3.");
-        TERN_(HAS_DISPLAY, ui.status_printf_P(0, PSTR(S_FMT " %i/3"), GET_TEXT(MSG_PROBING_MESH), int(i)));
+        if (verbose_level) SERIAL_ECHOLNPAIR("Probing point ", int(i + 1), "/3.");
+        TERN_(HAS_DISPLAY, ui.status_printf_P(0, PSTR(S_FMT " %i/3"), GET_TEXT(MSG_PROBING_MESH), int(i + 1)));
 
         // Retain the last probe position
         probePos = points[i];