make doxygen failed for 5.1.0

[sukanka]

When running make doxygen, I got the following errors

mkdir -p doc/api
doxygen -v
1.14.0
doxygen doxygen/doxygen.cfg
/build/stanmath/src/math-5.1.0/stan/math/fwd/functor/finite_diff.hpp:98: error: The following parameter of stan::math::finite_diff(const F &func, const TArgs &... args) is not documented:
  parameter 'args'
/build/stanmath/src/math-5.1.0/stan/math/rev/functor/apply_scalar_binary.hpp:60: error: The following parameter of stan::math::apply_scalar_binary(F &&f, T1 &&x, T2 &&y) is not documented:
  parameter 'y'
/build/stanmath/src/math-5.1.0/stan/math/rev/functor/apply_scalar_binary.hpp:82: error: The following parameter of stan::math::apply_scalar_binary(F &&f, T1 &&x, T2 &&y) is not documented:
  parameter 'y'
make: *** [makefile:81: doxygen] Error 1