I am attaching a patch that expands the documentation of isalnum, isalpha, isdecimal, isdigit, isnumeric, islower, isupper, and isspace.  I did not change isidentifier or isprintable because their docs were already complete.  I also left out istitle because I could not figure out how to deal with the  confusion between Python and Unicode notions of titlecase.

I would also like to note that it appears that isdigit and isdecimal imply isnumeric, so s.isalnum() is equivalent to all(c.isalpha() or c.isnumeric() for c in s).  However the actual code does have redundant checks for isdecimal() and isdigit().  I think the documentation should reflect what the code does for an off-chance that someone would replace unicodedata with their own database with which these checks are not redundant.