Docs: fix typo in documentation

[agoose77]

• Drop documentation of ak.highlevel.ArrayBuilder.extend
• Drop documentation of ak.layout.ArrayBuilder.extend
• Drop documentation of ak.layout.ArrayBuilder.append
• Fix typo of ArrayBuilder

[codecov]

Codecov Report

Merging #1326 (859daf9) into main (5613d44) will decrease coverage by 1.63%.
The diff coverage is 48.21%.

Impacted Files	Coverage Δ
src/awkward/_v2/_connect/cling.py	0.00% <0.00%> (ø)
src/awkward/_v2/contents/listoffsetarray.py	80.52% <ø> (+0.10%)	⬆️
src/awkward/_v2/operations/structure/ak_unzip.py	75.00% <ø> (ø)
...wkward/_v2/operations/structure/ak_argcartesian.py	73.33% <66.66%> (-1.67%)	⬇️
...ard/_v2/operations/structure/ak_argcombinations.py	76.92% <70.00%> (+1.92%)	⬆️
...wkward/_v2/operations/structure/ak_combinations.py	90.90% <87.50%> (+15.90%)	⬆️
...c/awkward/_v2/operations/structure/ak_cartesian.py	89.34% <89.07%> (+14.34%)	⬆️
src/awkward/_v2/_lookup.py	97.50% <97.50%> (ø)
src/awkward/_v2/__init__.py	100.00% <100.00%> (ø)
src/awkward/_v2/_connect/numba/arrayview.py	96.76% <100.00%> (+0.51%)	⬆️
... and 28 more

[jpivarski]

Yes, please drop references to the extend method, since that's an old one that was removed. It used to have a different meaning than just calling append many times, now it wouldn't, if it were to exist.

[agoose77]

I should have realised that it was just as likely that it was removed as added!

[jpivarski]

Thanks! If it's ready to go, you can merge it.