Fixed some urls in offline.yml file that wasn't yml formatted (kubern…

…etes-sigs#11127)

inventory/sample/group_vars/all/offline.yml

@@ -26,10 +26,10 @@
 ## Two options - Override entire repository or override only a single binary.
 
 ## [Optional] 1 - Override entire binary repository
-# github_url = "https://my_github_proxy"
-# dl_k8s_io_url = "https://my_dl_k8s_io_proxy"
-# storage_googleapis_url = "https://my_storage_googleapi_proxy"
-# get_helm_url = "https://my_helm_sh_proxy"
+# github_url: "https://my_github_proxy"
+# dl_k8s_io_url: "https://my_dl_k8s_io_proxy"
+# storage_googleapis_url: "https://my_storage_googleapi_proxy"
+# get_helm_url: "https://my_helm_sh_proxy"
 
 ## [Optional] 2 - Override a specific binary
 ## CNI Plugins