tls example without client certs?

[aaronkavlie-wf]

Issue description

TLS was a bit confusing because the example code includes a client cert & key. As per discussion here and the mysql client example here it's more common to connect without client cert/key. But without some explanation, the example code makes it look like this is required.

Configuration

Go version: go1.7.4 darwin/amd64

Server version: Amazon Aurora

[dveeden]

Maybe create a PR to update the docs?

[methane]

The example demonstrates RegisterTLSConfig() API.
Isn't it easy enough to know how to use "custom root CA" from "custom root CA + client cert" example.

Additionally, #543 or #564 will cover common cases.
I don't think adding more example is required for people who can't know A from A+B example.

[julienschmidt]

#564 is now merged. For most people it should just work "out of the box" with tls=true again. I think we can expect other people to know when they have to register their own config.