make flashing instructions a bit clearer

README.md

@@ -71,7 +71,7 @@ brew install dfu-util
 3. Put the transceiver into firmware flashing mode:
     1. Connect the board to your computer via USB
     2. Hold down the `flash` button
-    3. Press the `reset` button
+    3. Momentarily press the `reset` button
     4. Release the `flash` button
     5. The red LED will come on, then go off. If it stays on, it means your computer isn’t communicating with the board for some reason. Check your cable!
 4. Flash the firmware:
@@ -108,7 +108,7 @@ sudo udevadm control --reload-rules && sudo udevadm trigger
 ### Board setup
 1. Connect the board to your computer via USB
 2. Hold down the `flash` button
-3. Press the `reset` button
+3. Momentarily press the `reset` button
 4. Release the `flash` button
 
 The red LED will come on, then go off. If it stays on, it means your computer isn't communicating with the board for some reason. Check your cable!