doc: Update more docstrings to have one sentence summary as first line. Reviewed specfun, special-matrix, testfun, and time script directories. * scripts/specfun/expint.m, scripts/specfun/isprime.m, scripts/specfun/legendre.m, scripts/specfun/primes.m, scripts/specfun/reallog.m, scripts/specfun/realsqrt.m, scripts/special-matrix/gallery.m, scripts/special-matrix/hadamard.m, scripts/special-matrix/hankel.m, scripts/special-matrix/hilb.m, scripts/special-matrix/invhilb.m, scripts/special-matrix/magic.m, scripts/special-matrix/pascal.m, scripts/special-matrix/rosser.m, scripts/special-matrix/toeplitz.m, scripts/special-matrix/vander.m, scripts/special-matrix/wilkinson.m, scripts/testfun/assert.m, scripts/testfun/demo.m, scripts/testfun/example.m, scripts/testfun/fail.m, scripts/testfun/rundemos.m, scripts/testfun/runtests.m, scripts/testfun/speed.m, scripts/time/asctime.m, scripts/time/calendar.m, scripts/time/clock.m, scripts/time/ctime.m, scripts/time/datenum.m, scripts/time/datestr.m, scripts/time/datevec.m, scripts/time/etime.m, scripts/time/is_leap_year.m, scripts/time/now.m, scripts/time/weekday.m: Update more docstrings to have one sentence summary as first line.

--- a/scripts/special-matrix/wilkinson.m
+++ b/scripts/special-matrix/wilkinson.m
@@ -18,10 +18,11 @@
 
 ## -*- texinfo -*-
 ## @deftypefn {Function File} {} wilkinson (@var{n})
-## Return the Wilkinson matrix of order @var{n}.  Wilkinson matrices are
-## symmetric and tridiagonal with pairs of nearly, but not exactly, equal
-## eigenvalues.  They are useful in testing the behavior and performance
-## of eigenvalue solvers.
+## Return the Wilkinson matrix of order @var{n}.
+##
+## Wilkinson matrices are symmetric and tridiagonal with pairs of nearly, but
+## not exactly, equal eigenvalues.  They are useful in testing the behavior and
+## performance of eigenvalue solvers.
 ##
 ## @seealso{rosser, eig}
 ## @end deftypefn