Cherry pick Doctest for StructArray. to active_release

[alamb]

Automatic cherry-pick of 7fd7faf

• Originally appeared in Doctest for StructArray. #562: Doctest for StructArray.

[codecov-commenter]

Codecov Report

Merging #567 (6fdd31d) into active_release (8927982) will not change coverage.
The diff coverage is n/a.

@@               Coverage Diff               @@
##           active_release     #567   +/-   ##
===============================================
  Coverage           82.47%   82.47%           
===============================================
  Files                 167      167           
  Lines               46142    46142           
===============================================
  Hits                38056    38056           
  Misses               8086     8086           

Impacted Files	Coverage Δ
arrow/src/array/array_struct.rs	89.24% <ø> (ø)

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