doc: Update more docstrings to have one sentence summary as first line. Reviewed optimization, polynomial, signal script directories. * scripts/optimization/fminbnd.m, scripts/optimization/fminsearch.m, scripts/optimization/fminunc.m, scripts/optimization/fsolve.m, scripts/optimization/fzero.m, scripts/optimization/glpk.m, scripts/optimization/lsqnonneg.m, scripts/optimization/pqpnonneg.m, scripts/optimization/qp.m, scripts/optimization/sqp.m, scripts/polynomial/compan.m, scripts/polynomial/mkpp.m, scripts/polynomial/mpoles.m, scripts/polynomial/pchip.m, scripts/polynomial/poly.m, scripts/polynomial/polyaffine.m, scripts/polynomial/polyder.m, scripts/polynomial/polyeig.m, scripts/polynomial/polyfit.m, scripts/polynomial/polygcd.m, scripts/polynomial/polyint.m, scripts/polynomial/polyout.m, scripts/polynomial/polyval.m, scripts/polynomial/ppder.m, scripts/polynomial/ppint.m, scripts/polynomial/ppjumps.m, scripts/polynomial/ppval.m, scripts/polynomial/residue.m, scripts/polynomial/roots.m, scripts/polynomial/spline.m, scripts/polynomial/splinefit.m, scripts/polynomial/unmkpp.m, scripts/signal/arch_fit.m, scripts/signal/arch_rnd.m, scripts/signal/arma_rnd.m, scripts/signal/autoreg_matrix.m, scripts/signal/bartlett.m, scripts/signal/blackman.m, scripts/signal/detrend.m, scripts/signal/diffpara.m, scripts/signal/durbinlevinson.m, scripts/signal/fftconv.m, scripts/signal/fftfilt.m, scripts/signal/fftshift.m, scripts/signal/filter2.m, scripts/signal/freqz.m, scripts/signal/hamming.m, scripts/signal/hanning.m, scripts/signal/hurst.m, scripts/signal/ifftshift.m, scripts/signal/periodogram.m, scripts/signal/sinc.m, scripts/signal/sinetone.m, scripts/signal/sinewave.m, scripts/signal/spectral_adf.m, scripts/signal/spectral_xdf.m, scripts/signal/spencer.m, scripts/signal/stft.m, scripts/signal/synthesis.m, scripts/signal/unwrap.m, scripts/signal/yulewalker.m: Update more docstrings to have one sentence summary as first line.

--- a/scripts/optimization/qp.m
+++ b/scripts/optimization/qp.m
@@ -24,7 +24,9 @@
 ## @deftypefnx {Function File} {[@var{x}, @var{obj}, @var{info}, @var{lambda}] =} qp (@var{x0}, @var{H}, @var{q}, @var{A}, @var{b}, @var{lb}, @var{ub})
 ## @deftypefnx {Function File} {[@var{x}, @var{obj}, @var{info}, @var{lambda}] =} qp (@var{x0}, @var{H}, @var{q}, @var{A}, @var{b}, @var{lb}, @var{ub}, @var{A_lb}, @var{A_in}, @var{A_ub})
 ## @deftypefnx {Function File} {[@var{x}, @var{obj}, @var{info}, @var{lambda}] =} qp (@dots{}, @var{options})
-## Solve the quadratic program
+## Solve a quadratic program (QP).
+##
+## Solve the quadratic program defined by
 ## @tex
 ## $$
 ##  \min_x {1 \over 2} x^T H x + x^T q
@@ -60,16 +62,16 @@
 ## @noindent
 ## using a null-space active-set method.
 ##
-## Any bound (@var{A}, @var{b}, @var{lb}, @var{ub}, @var{A_lb},
-## @var{A_ub}) may be set to the empty matrix (@code{[]}) if not
-## present.  If the initial guess is feasible the algorithm is faster.
+## Any bound (@var{A}, @var{b}, @var{lb}, @var{ub}, @var{A_lb}, @var{A_ub})
+## may be set to the empty matrix (@code{[]}) if not present.  If the initial
+## guess is feasible the algorithm is faster.
 ##
 ## @table @var
 ## @item options
-## An optional structure containing the following
-## parameter(s) used to define the behavior of the solver.  Missing elements
-## in the structure take on default values, so you only need to set the
-## elements that you wish to change from the default.
+## An optional structure containing the following parameter(s) used to define
+## the behavior of the solver.  Missing elements in the structure take on
+## default values, so you only need to set the elements that you wish to
+## change from the default.
 ##
 ## @table @code
 ## @item MaxIter (default: 200)