Fix readme

- fix purchase URL
- adjust to the recent standard

keyboards/rura66/readme.md

@@ -7,16 +7,29 @@
 This is a simple left / right split keyboard with 66 keys. Supports reducing the burden on your shoulders.
 
 * Keyboard Maintainer: [T.Shinohara](https://github.com/ShinoharaTa)
-* Hardware Supported: The Shiro PCBs, ProMicro supported. Using Cherry MX 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)
+* Hardware Supported: The RURA PCB, ProMicro supported. Using Cherry MX Profile Switches.
+* Hardware Availability: [Booth (Japanese Site)](https://shino3.booth.pm/items/2643797)
+* 日本国内ではBoothで入手できます: [Booth (Japanese Site)](https://shino3.booth.pm/items/2643797)
 
 ![RURA66-USE](https://github.com/ShinoharaTa/keyboards/blob/master/RURA66/manual/images/IMG_0211.jpg?raw=true)
 
-Make for this keyboard default keymap (after setting up your build environment):
+Make example for this keyboard (after setting up your build environment):
 
  make rura66:default
 
+Flashing example for this keyboard:
+
+ make rura66:default:flash
+
 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).
 
+## Bootloader
+
+Enter the bootloader in 2 ways:
+
+* **Physical reset button**: Briefly press the button on the next to the TRRS jack.
+* **Keycode in layout**: Press the key mapped to `QK_BOOT` if it is available
+
+## Build Guide
+
 [Build guide - Japanese](https://github.com/ShinoharaTa/keyboards/blob/master/RURA66/manual/build_guide_ja.md)