config: Ignore description.md and metadata.yml (#284)
config: Ignore description.md and metadata.yml (#284)

They were created for #248, but since they're not in the ignore_pattern
they are being served.

See for proof:
http://x.exercism.io/v2/exercises/rust/luhn-from
http://x.exercism.io/v2/exercises/rust/luhn-trait

And note how description.md and metadata.yml appear inside the response.
sacherjj/rust,sacherjj/rust,exercism/xrust,petertseng/exercism-rust,exercism/xrust,petertseng/exercism-rust,petertseng/exercism-rust,sacherjj/rust