fix(ci/fetch-rust-docker): update comments

Author: rami3l

ci/fetch-rust-docker.bash

@@ -19,7 +19,7 @@ LOCAL_DOCKER_TAG="rust-$TARGET"
 # The following is a mapping from `$TARGET`s to cached Docker images built from `Dockerfile`s under
 # <https://github.com/rust-lang/rust/blob/master/src/ci/docker/host-x86_64/>,
 # e.g. `FROM rust-aarch64-unknown-linux-musl` means the base `Dockerfile` to look at is located under
-# <https://github.com/rust-lang/rust/blob/master/src/ci/docker/host-x86_64/dist-arm-linux>.
+# <https://github.com/rust-lang/rust/blob/master/src/ci/docker/host-x86_64/dist-arm-linux-musl>.
 case "$TARGET" in
   aarch64-unknown-linux-gnu)       image=dist-aarch64-linux ;;
   aarch64-unknown-linux-musl)      image=dist-arm-linux-musl ;;