Update helpful links

Marlin/Configuration.h

@@ -42,15 +42,19 @@
 //===========================================================================
 
 /**
- * Here are some standard links for getting your machine calibrated:
+ * Here are some useful links to help get your machine configured and calibrated:
  *
- * https://reprap.org/wiki/Calibration
- * https://youtu.be/wAL9d7FgInk
- * http://calculator.josefprusa.cz
- * https://reprap.org/wiki/Triffid_Hunter%27s_Calibration_Guide
- * https://www.thingiverse.com/thing:5573
- * https://sites.google.com/site/repraplogphase/calibration-of-your-reprap
- * https://www.thingiverse.com/thing:298812
+ * Example Configs:     https://github.com/MarlinFirmware/Configurations/branches/all
+ *
+ * Průša Calculator:    https://blog.prusaprinters.org/calculator_3416/
+ *
+ * Calibration Guides:  https://reprap.org/wiki/Calibration
+ *                      https://reprap.org/wiki/Triffid_Hunter%27s_Calibration_Guide
+ *                      https://sites.google.com/site/repraplogphase/calibration-of-your-reprap
+ *                      https://youtu.be/wAL9d7FgInk
+ *
+ * Calibration Objects: https://www.thingiverse.com/thing:5573
+ *                      https://www.thingiverse.com/thing:1278865
  */
 
 //===========================================================================