[*] make `Expect*` methods visible in the docs, closes #181

[pashagolub]

• rename pgxMockIface to Expecter
• rename pgxIface to PgxCommonIface
• move Config() methods to proper interfaces
• make expectation hidden

[MikeTaylor]

Aren't these interface renamings backwards-incompatible?

[pashagolub]

People should define their own interfaces in a real life. Even if they don't, the main interfaces are still the same: PgxConnIface and PgxPoolIface

[MikeTaylor]

This is probably the wrong place to discuss it, but I have never really understood why we are expected to define our own interfaces.

[pashagolub]

Because pgxmock is for tests only. I don't think, you want to have a testing module dependency in your production code. You are free to use it, of course.

And because the only interface in pgx is pgx.Tx

[MikeTaylor]

Thanks, I think that makes sense!