DOC: Update for return value of np.ptp() (#22276)
DOC: Update for return value of np.ptp() (#22276)

* Update documentation for return value of np.ptp()

* Update integer value to scalar to accomodate other numeric data types

* Add examples to np.char.isdigit()

* Remove extra space and example

Closes gh-18719
mattip/numpy,charris/numpy,numpy/numpy,numpy/numpy,mattip/numpy,mattip/numpy,charris/numpy,numpy/numpy,endolith/numpy,mhvk/numpy,endolith/numpy,charris/numpy,mattip/numpy,endolith/numpy,mhvk/numpy,mhvk/numpy,mhvk/numpy,charris/numpy,endolith/numpy,mhvk/numpy,numpy/numpy