Remove \nonstable yet. The stability rules for Eigen3 are much simpler:

- all what's not in unsupported/ is considered stable API
    (except internal stuff e.g. expression templates).

doc/Doxyfile.in

@@ -209,7 +209,6 @@ ALIASES                = "only_for_vectors=This is only for vectors (either row-
                          "redstar=<a href='#warningarraymodule' style='color:red;text-decoration: none;'>*</a>" \
                          "matrixworld=<a href='#matrixonly' style='color:green;text-decoration: none;'>*</a>" \
                          "arrayworld=<a href='#arrayonly' style='color:blue;text-decoration: none;'>*</a>" \
-                         "nonstableyet=\warning This is not considered to be part of the stable public API yet. Changes may happen in future releases. See \ref Experimental \"Experimental parts of Eigen\"" \
                          "note_about_arbitrary_choice_of_solution=If there exists more than one solution, this method will arbitrarily choose one." \
                          "note_about_using_kernel_to_study_multiple_solutions=If you need a complete analysis of the space of solutions, take the one solution obtained by this method and add to it elements of the kernel, as determined by kernel()." \
                          "note_about_checking_solutions=This method just tries to find as good a solution as possible. If you want to check whether a solution exists or if it is accurate, just call this function to get a result and then compute the error of this result, or use MatrixBase::isApprox() directly, for instance like this: \code bool a_solution_exists = (A*result).isApprox(b, precision); \endcode This method avoids dividing by zero, so that the non-existence of a solution doesn't by itself mean that you'll get \c inf or \c nan values." \