Update guideline for comments for interface implementation.

[Gilthoniel]

No description provided.

[nkcr]

For the record, we went through many possibilities:

// Stream belongs to the mino.RPC implementation
// Stream implements mino.RPC.Stream
// Stream implements mino.RPC.Stream()
// Stream implements mino.RPC
// Stream contributes to mino.RPC
// Stream contributes to implementing mino.RPC
// Stream belongs to the mino.RPC interface
// Stream is an element of the mino.RPC interface
// Stream is a member of mino.RPC
// Stream belongs to mino.RPC
// Stream belongs to interface mino.RPC
// Stream belongs to mino.RPC interface

And we choose to favour a concise and easy to remember phrasing with // Stream implements mino.RPC even if that may not be a 100% technically true. We believe it is better to have simple rules that are followed instead of complex ones that we don't use.
Some discussion here #13 (comment).

[nkcr]

I would add something to handle more complex situation, like:

For some situation, it is necessary to add detailed information about a test case. This can be done between the SCOPE and the FUNCTION:

func Test_RPC_MultipleSimple_Stream(t *testing.T) {
...
}

As an invariant, the SCOPE and FUNCTION should always be the first, respectively the last, element.

[Gilthoniel]

Done