[Keyboard] Add soda/mango (#21100)

Co-authored-by: jack <0x6a73@protonmail.com>
Co-authored-by: Joel Challis <git@zvecr.com>

keyboards/soda/mango/readme.md

@@ -0,0 +1,23 @@
+# mango-17
+
+A customizable 17  keyboard, support both HOTSWAP and SOLDER.
+
+* Keyboard Maintainer: [gezhaoyou](https://github.com/gezhaoyou)
+* Hardware Supported: [gezhaoyou](https://github.com/gezhaoyou)
+
+Make example for this keyboard (after setting up your build environment):
+
+    make soda/mango:default
+
+Flashing example for this keyboard:
+
+    make soda/mango: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: [boot] first, then press button: [reset]  on the back of the PCB
+* **Keycode in layout**: Press the key mapped to `QK_BOOT` if it is available