doc: quote wget URLs to avoid copy paste escapes

Also makes the code `shellcheck`-compliant.

Signed-off-by: Anatoli Babenia <[email protected]>

docs/getting-started.md

@@ -103,13 +103,13 @@ ARCH="$(uname -m)"
 latest=$(wget "http://spec.ccfc.min.s3.amazonaws.com/?prefix=firecracker-ci/v1.10/x86_64/vmlinux-5.10&list-type=2" -O - 2>/dev/null | grep "(?<=<Key>)(firecracker-ci/v1.10/x86_64/vmlinux-5\.10\.[0-9]{3})(?=</Key>)" -o -P)
 
 # Download a linux kernel binary
-wget https://s3.amazonaws.com/spec.ccfc.min/${latest}
+wget "https://s3.amazonaws.com/spec.ccfc.min/${latest}"
 
 # Download a rootfs
-wget https://s3.amazonaws.com/spec.ccfc.min/firecracker-ci/v1.10/${ARCH}/ubuntu-22.04.ext4
+wget "https://s3.amazonaws.com/spec.ccfc.min/firecracker-ci/v1.10/${ARCH}/ubuntu-22.04.ext4"
 
 # Download the ssh key for the rootfs
-wget https://s3.amazonaws.com/spec.ccfc.min/firecracker-ci/v1.10/${ARCH}/ubuntu-22.04.id_rsa
+wget "https://s3.amazonaws.com/spec.ccfc.min/firecracker-ci/v1.10/${ARCH}/ubuntu-22.04.id_rsa"
 
 # Set user read permission on the ssh key
 chmod 400 ./ubuntu-22.04.id_rsa