[Keyboard] Add Obro (#15884)

Co-authored-by: Drashna Jaelre <drashna@live.com>
Co-authored-by: Ryan <fauxpark@gmail.com>

keyboards/handwired/obro/readme.md

@@ -0,0 +1,22 @@
+# Obro
+
+* Keyboard Maintainer: [Holten Campbell](https://github.com/holtenc)
+* Hardware Supported: ATMEGA32u4
+* Hardware Availability: Not applicable
+
+Make example for this keyboard (after setting up your build environment):
+
+    make handwired/obro:default
+
+Flashing example for this keyboard:
+
+    make handwired/obro: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 3 ways:
+* Bootmagic reset: HOld down the key at (0,0) in the matrix (usually the top left key or Escape) and plug in the keyboard
+* Physical reset button: Briefly press the button on the back of the PCB
+* Keycode in layout: Press the key mapped to RESET if it is available