doc: u0, p keyword arg in solve()

[daviehh]

Checklist

• Appropriate tests were added
• Any code changes were done in a way that does not break public API
• All documentation related to code changes were updated
• The new code follows the
  contributor guidelines, in particular the SciML Style Guide and
  COLPRAC.
• Any new documentation only uses public API

Additional context

Documentation change: add doc for the u0 and p keyword arguments in the solve call, e.g. as used in

https://docs.sciml.ai/SciMLSensitivity/stable/manual/differential_equation_sensitivities/#Using-and-Controlling-Sensitivity-Algorithms-within-AD