DOC: Add missing API item to reference docs
- [x] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).

* `Float32/64Dtype` & `arrays.FloatingArray`
* `NaT` & `NA`
* `lreshape`
* `set_eng_float_format`
* `NamedAgg`

Will merge in a few days if no further comments.