Update flashing instructions

Author: kesyog

doc/src/SUMMARY.md

@@ -3,6 +3,7 @@
 [Hangman](./README.md)
 
 - [Development]()
+- [Flashing](./flashing.md)
 - [Hardware]()
 - [Assembly](./assembly.md)
 - [Bringup](./bringup.md)

doc/src/flashing.md

@@ -0,0 +1,24 @@
+# Flashing the firmware
+
+## Prereqs
+
+* Obtain a Segger J-Link debugger
+* Download the [nRF Command Line Tools](https://www.nordicsemi.com/Products/Development-tools/nRF-Command-Line-Tools)
+* Download the SoftDevice s113 from <https://www.nordicsemi.com/Products/Development-software/S113>
+
+## Instructions
+
+1. Connect your debugger.
+1. Flash the SoftDevice. This generally only needs to be done once.
+
+   ```sh
+   nrfjprog --family nrf52 --program s113_nrf52_7.2.0_softdevice.hex --chiperase --verify --reset
+   ```
+
+   Your .hex filename may differ. Note that Nordic encourages the use of the nRF Util over nrfjprog.
+   I've found nrfjprog to be more reliable. YMMV.
+1. Flash the hangman firmware:
+
+   ```sh
+   DEFMT_LOG=info cargo run --release --bin proto1_0 --features nrf52832
+   ```

hangman/flash.sh

@@ -13,6 +13,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+# This is a helper script to flash the nrf52 USB stick developer module
 
 TMPFILE=$(mktemp /tmp/hangman.XXXXXX.zip)