updated readme.md of yushakobo/quick7 keyboard (#10243)

* update "Hardware Availability"

* add a section of "How to build"

* update "Hardware Supported"

keyboards/yushakobo/quick7/readme.md

@@ -5,8 +5,11 @@
 A simple macropad for the beginners.
 
 * Keyboard Maintainer: [yushakobo](https://github.com/yushakobo)
-* Hardware Supported: quick7, Pro Micro (ATmega32U4)
-* Hardware Availability: (Under Preparation)
+* Hardware Supported: quick7 PCB, Pro Micro (ATmega32U4)
+* Hardware Availability: [yushakobo Shop](https://yushakobo.jp/shop/quick7/)
+
+## How to build
+* Build guide available [here](https://github.com/yushakobo/build-documents/blob/master/Quick7/Buildguide-en.md). (Japanese build guide is [here](https://github.com/yushakobo/build-documents/blob/master/Quick7/BuildGuide.md).)
 
 Make example for this keyboard (after setting up your build environment):