docs: improve doctests for ndarray instances in `blas/sdot` #27447

Job	Run time
Check for project conventions label	0s
Check for Git History label	0s
Check for stale label	0s
Check for contributor guidelines label	0s
Check for spam label	-1s
Check for EditorConfig label	-6s
Check for already resolved label	-7s
	-14s

Provide feedback