Show `es-mx` in the language drop-down

[delphiactual]

Closes #31

[netlify[bot]]

Deploy request for destiny-data-explorer accepted.

Accepted with commit 61c9b88271c0ea2e9613b9109acff6b7a3aae396

https://app.netlify.com/sites/destiny-data-explorer/deploys/606e33eed122110007774ae7