Add a mark to all inline content between two positions.
Ports AddMarkStep from prosemirror-transform/src/mark_step.ts.
Summary
Functions
Create a new AddMarkStep.
Types
@type t() :: %ProsemirrorEx.Transform.AddMarkStep{ from: non_neg_integer(), mark: ProsemirrorEx.Model.Mark.t(), to: non_neg_integer() }