CoinGecko maintains an exchanges listing at https://www.coingecko.com/en/exchanges.
Kindly check for pending exchanges listing before posting for new listing at our github: https://github.com/coingecko/cryptoexchange.
To have your exchange listed, do fill up this form: https://goo.gl/forms/E3gSco9bWHPv8Ili2
Listing is free but CoinGecko will verify the trading volume and credibility of the exchange before adding it.
If you have a Ruby developer, feel free to make a pull request for faster implementation.