[Keyboard] Add dnworks/SBL (#20652)

Co-authored-by: Less/Rikki <86894501+lesshonor@users.noreply.github.com>
Co-authored-by: Drashna Jaelre <drashna@live.com>

keyboards/dnworks/sbl/readme.md

@@ -0,0 +1,27 @@
+# SBL
+
+![SBL](https://i.imgur.com/HqRfr4bh.jpg)
+
+An O ring mount 60%, akin to the otd 356mini
+
+* Keyboard Maintainer: [Zeix](https://github.com/itsme-zeix)
+* Hardware Supported: SBL Solder PCB rev1
+* Hardware Availability: https://dnworks.co/products/sbl
+
+Make example for this keyboard (after setting up your build environment):
+
+    make dnworks/sbl:default
+
+Flashing example for this keyboard:
+
+    make dnworks/sbl: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**: Short the 'USB_BOOT' button and plug in keyboard or briefly short the `RESET` and `GND` pads on the SWD header twice
+* **Keycode in layout**: Press the key mapped to `QK_BOOT` if it is available