docs(vscode/project-config): make elf field optional #163

Author: urish

docs/vscode/project-config.md

@@ -30,6 +30,8 @@ The extension of the firmware file depends on the board you are using:
 | ESP32 Family               | .bin, .uf2, .elf, flasher_args.json |
 | STM32 Family               | .hex, .bin, .elf                    |
 
+The `elf` field is optional, but providing it can speed up the simulation in some cases.
+
 You check test your configuration by pressing **F1** and then selecting "**Wokwi: Start Simulator**". Make sure you compile your program before starting the simulation.
 
 :::warning