[2.0.x] Enable PIDTEMPBED in Anet A8 example config (#12655)

Marlin/src/config/examples/Anet/A8/Configuration.h

  * heater. If your configuration is significantly different than this and you don't understand
  * the issues involved, don't use bed PID until someone else verifies that your hardware works.
  */
-//#define PIDTEMPBED
+#define PIDTEMPBED
 
-#define BED_LIMIT_SWITCHING
+//#define BED_LIMIT_SWITCHING
 
 /**
  * Max Bed Power
 
   //120V 250W silicone heater into 4mm borosilicate (MendelMax 1.5+)
   //from FOPDT model - kp=.39 Tp=405 Tdead=66, Tc set to 79.2, aggressive factor of .15 (vs .1, 1, 10)
-  #define DEFAULT_bedKp 10.00
-  #define DEFAULT_bedKi .023
-  #define DEFAULT_bedKd 305.4
+  //#define DEFAULT_bedKp 10.00
+  //#define DEFAULT_bedKi .023
+  //#define DEFAULT_bedKd 305.4
 
   //120V 250W silicone heater into 4mm borosilicate (MendelMax 1.5+)
   //from pidautotune
   //#define DEFAULT_bedKi 1.41
   //#define DEFAULT_bedKd 1675.16
 
+  // ANET A8
+  // original Bed + 0.3mm Heat conducting into 4mm borosilicate (PID-Autotune: M303 E-1 S60 C5):
+  #define DEFAULT_bedKp 295.00
+  #define DEFAULT_bedKi 35.65
+  #define DEFAULT_bedKd 610.21
+
   // FIND YOUR OWN: "M303 E-1 C8 S90" to run autotune on the bed at 90 degreesC for 8 cycles.
 #endif // PIDTEMPBED