Consider referencing snowflake-pool in README for connection pooling

[jorshali]

I wrote a wrapper around snowflake-promise that makes it easy to integrate connection pooling. The library uses generic-pool under the covers. You can find the project details here:

https://github.com/jorshali/snowflake-pool

And the npm module here:

https://www.npmjs.com/package/snowflake-pool

If you would like me to write the blurb, just let me know! Happy to contribute.