DOC: clarifications + comment step size theta
DOC: clarifications + comment step size theta

DOC: fix wording

enhance return name

vighneshbirodkar/scikit-image,Hiyorimi/scikit-image,ajaybhat/scikit-image,rjeli/scikit-image,ajaybhat/scikit-image,ofgulban/scikit-image,paalge/scikit-image,paalge/scikit-image,ofgulban/scikit-image,rjeli/scikit-image,paalge/scikit-image,vighneshbirodkar/scikit-image,ofgulban/scikit-image,Hiyorimi/scikit-image,rjeli/scikit-image,vighneshbirodkar/scikit-image