docs(setup): remove extra slash from Fedora toolchain install command

docs/docs/development/setup.md

@@ -318,7 +318,7 @@ To build firmwares for the ARM architecture (all supported MCUs/keyboards at thi
 export ZSDK_VERSION=0.11.4
 wget -q "https://github.com/zephyrproject-rtos/sdk-ng/releases/download/v${ZSDK_VERSION}/zephyr-toolchain-arm-${ZSDK_VERSION}-setup.run" && \
  sh "zephyr-toolchain-arm-${ZSDK_VERSION}-setup.run" --quiet -- -d ~/.local/zephyr-sdk-${ZSDK_VERSION} && \
- rm "zephyr-toolchain-arm-\${ZSDK_VERSION}-setup.run"
+ rm "zephyr-toolchain-arm-${ZSDK_VERSION}-setup.run"
 ```
 
 The installation will prompt with several questions about installation location, and creating a default `~/.zephyrrc` for you with various variables. The defaults should normally work as expected.