changed arm-none-eabi-gdb to gdb-multiarch

.cargo/config

@@ -1,5 +1,5 @@
 [target.thumbv7m-none-eabi]
-runner = 'arm-none-eabi-gdb'
+runner = 'gdb'
 rustflags = [
   "-C", "link-arg=-Tlink.x",
 ]

README.md

@@ -25,7 +25,7 @@ mini](https://www.st.com/en/development-tools/stlink-v3mini.html) for programmin
 
 To program your microcontroller, you need to install:
 - [openocd](http://openocd.org/)
-- `arm-none-eabi-gdb`
+- `gdb`
 
 Finally, you need to install arm target support for the Rust compiler. To do
 so, run