doc: Review and update documentation for "Matrix Manipulation" chapter. * matrix.txi, arrayfun.m, blkdiag.m, fliplr.m, flipud.m, logspace.m, postpad.m, prepad.m, randi.m, repmat.m, rot90.m, rotdim.m, shiftdim.m, sortrows.m, vech.m, xor.m, hadamard.m, hankel.m, hilb.m, invhilb.m, magic.m, pascal.m, rosser.m, sylvester_matrix.m, toeplitz.m, vander.m, wilkinson.m, bsxfun.cc, find.cc, lookup.cc, rand.cc, tril.cc, data.cc, arrayfun.m, blkdiag.m, fliplr.m, flipud.m, logspace.m, postpad.m, prepad.m, randi.m, repmat.m, rot90.m, rotdim.m, shiftdim.m, sortrows.m, vech.m, xor.m, hadamard.m, hankel.m, hilb.m, invhilb.m, magic.m, pascal.m, rosser.m, sylvester_matrix.m, toeplitz.m, vander.m, wilkinson.m, bsxfun.cc (bsxfun), find.cc (find), lookup.cc (lookup), rand.cc (rand, randn, rande, randg, randp), tril.cc (triu), data.cc (all, any, horzcat, vertcat, cat, permute, ipermute, ones, zeros, eye, linspace, resize, reshape, issorted, diff): Improve docstrings

--- a/scripts/general/shiftdim.m
+++ b/scripts/general/shiftdim.m
@@ -19,7 +19,7 @@
 ## -*- texinfo -*-
 ## @deftypefn  {Function File} {@var{y} =} shiftdim (@var{x}, @var{n})
 ## @deftypefnx {Function File} {[@var{y}, @var{ns}] =} shiftdim (@var{x})
-## Shift the dimension of @var{x} by @var{n}, where @var{n} must be
+## Shift the dimensions of @var{x} by @var{n}, where @var{n} must be
 ## an integer scalar.  When @var{n} is positive, the dimensions of
 ## @var{x} are shifted to the left, with the leading dimensions
 ## circulated to the end.  If @var{n} is negative, then the dimensions