gh-98657: [docs] `array.typecodes` is a module-level attribute (GH-98729)

* gh-98657: [docs] `array.typecodes` is a module-level attribute

* Update array.rst
(cherry picked from commit c144e57b316e97a58ed5ad813c847fa8d2341dd7)

Co-authored-by: Nikita Sobolev <mail@sobolevn.me>