Moco cheatsheet contains wrong Matlab call

[jenniferMaier]

According to the Moco cheatsheet (https://github.com/opensim-org/opensim-moco/blob/master/Moco/doc/MocoCheatSheet.pdf) the Matlab command for setting the max number of iterations of a solver is solver.set_max_iterations(500);. This results in an error message in Matlab. The correct call should be solver.set_optim_max_iterations(500);.