improved python documentation
improved python documentation

MMesch/SHTOOLS,MarkWieczorek/SHTOOLS,ioshchepkov/SHTOOLS,ian-r-rose/SHTOOLS,heroxbd/SHTOOLS,pochoi/SHTOOLS,SHTOOLS/SHTOOLS,MarkWieczorek/SHTOOLS,ian-r-rose/SHTOOLS,SHTOOLS/SHTOOLS,pochoi/SHTOOLS,heroxbd/SHTOOLS