Add Nim to other languages doc.

doc/otherlang.md

@@ -29,6 +29,7 @@ project's documentation for details.
 * [Javascript](https://github.com/popham/capnp-js-base) by [@popham](https://github.com/popham)
 * [Javascript](https://github.com/jscheid/capnproto-js) (older, abandoned) by [@jscheid](https://github.com/jscheid)
 * [Lua](https://github.com/cloudflare/lua-capnproto) by [CloudFlare](http://www.cloudflare.com/) / [@calio](https://github.com/calio)
+* [Nim](https://github.com/zielmicha/capnp.nim) by [@zielmicha](https://github.com/zielmicha)
 * [OCaml](https://github.com/pelzlpj/capnp-ocaml) by [@pelzlpj](https://github.com/pelzlpj)
 * [Ruby](https://github.com/cstrahan/capnp-ruby) by [@cstrahan](https://github.com/cstrahan)