[Keyboard] add macro pad "Shiro" (#6338)

* add keyboard new macro pad "Kuro"

* change main readme.md

* remove not used code from default/keymap.c

* Remove unnecessary code

* Supports info.json

* removed back slash and not used functions.

* update at product link. add japanese messages.

keyboards/shiro/readme.md

@@ -0,0 +1,27 @@
+# 素 - Shiro 
+
+![Shiro](https://cdn.discordapp.com/attachments/536423734144401422/597447002288291861/P7070070_cp.jpg)
+
+これは日本の名刺(55mmx91mm)に、3x5の15キーを詰め込んだとても小さいキーパッドです。
+
+This product is a 3x5 very small keypad.
+It is made in 55mm x 91mm according to the Japanese business card.
+
+Keyboard Maintainer: [T.Shinohara](https://github.com/ShinoharaTa)  
+Hardware Supported:  The Shiro PCBs, ProMicro supported. Using only Kailh Low Profile Switches.  
+Hardware Availability: [Booth (Japanese Site)](https://shino3.booth.pm/items/1444895)  
+日本国内ではBoothで入手できます: [Booth (Japanese Site)](https://shino3.booth.pm/items/1444895)
+
+![Shiro-backside](https://cdn.discordapp.com/attachments/536423734144401422/597464086640328724/20190707_033520.jpg)
+
+Make for this keyboard default keymap (after setting up your build environment):
+
+    make shiro:default
+
+Make for this keyboard build check keymap (after setting up your build environment):
+
+    make shiro:check
+
+See the [build environment setup](https://docs.qmk.fm/#/getting_started_build_tools) and the [make instructions](https://docs.qmk.fm/#/getting_started_make_guide) for more information. Brand new to QMK? Start with our [Complete Newbs Guide](https://docs.qmk.fm/#/newbs).
+
+[Build guide - Japanese](https://github.com/ShinoharaTa/keyboards/blob/master/Shiro/manual/build_guide_ja.md)