table renaming is undocumented and confusing

[tv42]

I have an M:N relation table named users_widgets. It gets named UsersWidget by the logic to make it singular; that's not great.

I couldn't find any documentation that table renaming is possible.

Then I stumbled on #435 and more importantly e30cde1

Based on that, it seems

1. There's no way to rename a struct field X differently than a table name X

2. And looking at that, I realized struct fields also cannot be renamed differently for two different struct types.

3. Table names go through the renaming after Singular. That means I need rename: users_widget: blah. That's confusing; the key is neither present in my database nor in the default generated code.

4. And, where we started from, none of this is documented.