doc: incorporate Go reference document changes for Alpha release

[jyyi1]

No description provided.

[maddyhof]

Reviewed against the doc from Hilary and identified a bunch of formatting things that were not implemented. Nothing is critical but I flagged as many as I could. Happy to review again once those changes are in and confirm that nothing else is amiss.

[jyyi1]

Thanks @maddyhof , these are all Godoc specific formats, and there are some restrictions: for example, only type names can be wrapped by [] but not method names. Also typically we don't wrap a type with [] in the documentation that describes the type itself (example, the Closer is not wrapped in [] in io.Closer). Similarly, we won't add backticks "`" to most of the names, unless it is a local function parameter.

[maddyhof]

As discussed, feel free to ignore my comments that don't make sense in the Go style, and reject Hilary's suggestions in the doc so that we know which things aren't going to be implemented.