documentation edit, X0

[smitdave]

Looking at the webpage:

https://dd-harp.github.io/exDE/reference/make_parameters_X_SIS.html

X0 should be called the "initial size..."

[slwu89]

After software meeting today, make a list of things to do and tag this as one of them. It will likely be changed anyway as we separate parameter specification from setting of initial conditions.