update docs

[GertjanBisschop]

Update docs on additional_nodes flags and correct type in api.md.

[codecov]

Codecov Report

Merging #2194 (33ac934) into main (25b1aee) will not change coverage.
The diff coverage is n/a.

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@@           Coverage Diff           @@
##             main    #2194   +/-   ##
=======================================
  Coverage   91.46%   91.46%           
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  Files          20       20           
  Lines       11254    11254           
  Branches     2297     2297           
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  Hits        10293    10293           
  Misses        523      523           
  Partials      438      438           

Flag	Coverage Δ
C	91.46% <ø> (ø)
python	98.68% <ø> (ø)

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Files Changed	Coverage Δ
msprime/ancestry.py	98.66% <ø> (ø)

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[petrelharp]

I made some suggestions to make it more precise; if you see a good way to have an even more precise (and pedantic?) definition of what exactly the node flags record somewhere, that could still be good.

[GertjanBisschop]

Thanks a lot @petrelharp!

[jeromekelleher]

LGTM, happy to merge whenever

[petrelharp]

Thanks! Looks good.