Tweak short-fn docstring
```
Shorthand for fn. Arguments are given as $n, where n is the 0-indexed
argument of the function. $ is also an alias for the first (index 0) argument.
- The $& symbol will make the anonymous function variadic if it apears in the
+ The $& symbol will make the anonymous function variadic if it appears in the
body of the function - it can be combined with positional arguments.
Example usage:
