Fix node label inconsistencies

[loopspace]

Reported via email:

I noticed that the documentation mentions an anchor named between first and last incoming, but the code names this anchor as between first incoming and last incoming.
Meanwhile, the dual anchor (between first and last outgoing) works as intended.
The other "incorrect" anchor, between first outgoing and last outgoing, doesn't exist.
I think you get why that can be confusing!

Would you mind making two aliases, so that both versions are correct, and in that way we have both consistency and backwards compatibility?
That is, making between first and last incoming an alias for between first incoming and last incoming, and making between first outgoing and last outgoing an alias for between first and last outgoing.
I don't know much about the inner workings of tikz, but I assume this is an easy fix.

If you cannot for whatever reason, a small update to the documentation to inform users of this pitfall (without changing any of the code or breaking existing documents) would be nice.