Documentation: MultiBlock class does not describe the ways it can be instantiated

[MatthewFlamm]

Most of the other pyvista data classes have examples that explain the possible ways of instantiating the class like Rectlinear Grid. MultiBlock does not have such a set of descriptions. I had to go to the source code to see the options.

[banesullivan]

Thanks for pointing this out! Will fix

[banesullivan]

Just added some changes that should give insight into how you can instantiate these objects from lists and dictionaries which will be live at https://docs.pyvista.org/core/composite.html#pyvista.MultiBlock in about 20-30 minutes

[MatthewFlamm]

Looks great!