4.4.1 One of the touch commands has invalid extension

In this part

```bash
mkdir -p leapyears/src/leapyears
mkdir -p leapyears/target/public
touch leapyears/target/public/index.html
touch leapyears/src/leapyears/core.cljs
touch leapyears/tools.cljs
touch leapyears/deps.edn
```

there is a command

```
touch leapyears/tools.cljs
```

but should be

```
touch leapyears/tools.clj
```

(without "s" at the end).