PR for JumpProblem, SSAStepper, and Jump types docstrings and doctests.

[00krishna]

This PR updates the specific docstrings below. This is a first PR, to also confirm that the template and updates look good. Once everything looks good, I can continue to update the rest of the docstrings.

Updated docstrings and docstests for JumpProblem, SSAStepper, MassActionJump, ConstantRateJump, VariableRateJump, and RegularJump. Also added strict doctest checks in make.jl. Added StableRNGs, and LinearAlgebra to Project.toml for docs, as a necessary requirement for some doctests.