Add notes about cargo run options.

Author: thejpster

.cargo/config.toml

@@ -1,6 +1,8 @@
 [target.thumbv6m-none-eabi]
+# This will make a UF2 and copy it to the RP2040's Mass Storage Device bootloader
 # runner = "elf2uf2-rs -d"
-runner = "probe-run-rp --chip RP2040"
+# This will flash over SWD with any compatible probe it finds. You need 0.3.1 or higher for RP2040 support.
+runner = "probe-run --chip RP2040"
 
 rustflags = [
   # This is needed if your flash or ram addresses are not aligned to 0x10000 in memory.x