Reformat all code to use shell instead of sh

snippets/switch-to-last-branch.md

@@ -7,11 +7,11 @@ Switches back to the last branch.
 
 - Use `git checkout -` to switch back to the previous branch.
 
-```sh
+```shell
 git checkout -
 ```
 
-```sh
+```shell
 git checkout patch-1
 git checkout master
 git checkout - # Switches to `patch-1`