Re: doc: Bring mention of unique index forced transaction wait behavior outside of the internal section

Hi David,

> It's basically a glorified cross-reference.  I didn't dislike directing the reader to the internals section enough to try and establish a better location for the main content.

One problem I see is that:

+ [..], but as there is no pre-existing data, visibility checks are unnecessary.

... allows a wide variety of interpretations, most of which will be
wrong. And all in all I find an added paragraph somewhat cryptic.

If the goal is to add a cross-reference I suggest keeping it short,
something like "For additional details on various corner cases please
see ...".