Add missing hardware availability for Plank EZ (#11069)

Add missing information needed to mirror the supported hardware in the previous line

keyboards/planck/readme.md

@@ -7,7 +7,7 @@ A compact 40% (12x4) ortholinear keyboard kit made and sold by OLKB and Massdrop
 
 Keyboard Maintainer: [Jack Humbert](https://github.com/jackhumbert)  
 Hardware Supported: Planck PCB rev1, rev2, rev3, rev4, rev5, rev6; Planck Light, Planck EZ  
-Hardware Availability: [OLKB.com](https://olkb.com), [Massdrop](https://www.massdrop.com/buy/planck-mechanical-keyboard?mode=guest_open)
+Hardware Availability: [OLKB.com](https://olkb.com), [Massdrop](https://www.massdrop.com/buy/planck-mechanical-keyboard?mode=guest_open), [Ergodox (Planck EZ)](https://ergodox-ez.com/pages/planck)
 
 Make example for this keyboard (after setting up your build environment):