capture NLL link (#1238)
capture NLL link (#1238)

From [discussion](https://github.com/exercism/rust/pull/1236/files#r613621861)

I generated the start of it using the following nushell script:

```nu
echo [[description, url]; ['Non-lexical lifetimes', 'https://doc.rust-lang.org/edition-guide/rust-2018/ownership-and-lifetimes/non-lexical-lifetimes.html']] | to json --pretty 2
```

I still cannot figure out how to append to a `[]` in a file in nu.
petertseng/exercism-rust,exercism/xrust,petertseng/exercism-rust,petertseng/exercism-rust,exercism/xrust