Update docstrings from np.array to np.ndarray

[angela97lin]

Closes #1394; np.array refers to the method used to create an array and np.ndarray is the actual data structure.

[codecov]

Codecov Report

Merging #1417 (f1bb6e1) into main (4e2b8fc) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main    #1417   +/-   ##
=======================================
  Coverage   100.0%   100.0%           
=======================================
  Files         214      214           
  Lines       14133    14133           
=======================================
  Hits        14126    14126           
  Misses          7        7           

Impacted Files	Coverage Δ
evalml/data_checks/class_imbalance_data_check.py	100.0% <ø> (ø)
evalml/data_checks/high_variance_cv_data_check.py	100.0% <ø> (ø)
evalml/data_checks/highly_null_data_check.py	100.0% <ø> (ø)
evalml/data_checks/invalid_targets_data_check.py	100.0% <ø> (ø)
evalml/model_understanding/graphs.py	100.0% <ø> (ø)
evalml/objectives/objective_base.py	100.0% <ø> (ø)
evalml/pipelines/binary_classification_pipeline.py	100.0% <ø> (ø)
evalml/pipelines/classification_pipeline.py	100.0% <ø> (ø)
evalml/pipelines/components/component_base.py	100.0% <ø> (ø)
...lines/components/ensemble/stacked_ensemble_base.py	100.0% <ø> (ø)
... and 10 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 4e2b8fc...f1bb6e1. Read the comment docs.

[freddyaboulton]

Nice! I think you caught them all!

[dsherry]

Good call! 🚢