fix hljslang target

[ta-kiyama]

summary

When I wrote code language that is alias for another language in markdown, I caught a 404 link for hightlight.js.

demo: https://jsfiddle.net/qf7gLw3a/745/ (see F12 developper tools)

markdown

    load `https://cdnjs.cloudflare.com/ajax/libs/highlight.js/9.12.0/languages/v.min.js` ← 404

    ```v
    // wrong loading!! ("v" is an alias for "verilog")

----

load `https://cdnjs.cloudflare.com/ajax/libs/highlight.js/9.12.0/languages/verilog.min.js` ← 200

```verilog
// good loading
```

# actual request

![default](https://user-images.githubusercontent.com/38449628/44826507-4af61a00-ac4a-11e8-81a0-fa18a6692ca2.png)

[hinesboy]

感谢！