Wrong formula in fluids.fittings.contraction_conical docs

[f-merlo]

Hello Caleb,

thanks for the great work. I point out a little typo on the fluids.fittings.contraction_conical docs:

.. math:: K_{conv,2} = 0.06961+C_B(\sin(\alpha/2)-1)\lambda^2 + (\lambda-1)^2

That is the K formula for the fluids.fittings.contraction_beveled.

Should be:

.. math:: K_{conv,2} = 0.0696\sin(\alpha/2)(1-\beta^5)\lambda^2 + (\lambda-1)^2

However, the implementation in the code is correct