[Doc] Adding an unknown mark doesn't produce an error (#1597)
[Doc] Adding an unknown mark doesn't produce an error (#1597)

The *Applying custom formatting* guide states that Slate outputs an error in the console when a mark is applied without a corresponding renderer but AFAIK, that's not the case in the current version. I'm guessing this is an old behaviour (I'm completely new to this library), hence the doc update.
isubastiCadmus/slate,ashutoshrishi/slate,ianstormtaylor/slate,ianstormtaylor/slate