Add to docs: Grouping Shapes with Shape.Name

[blewjy]

When developing new features, we found some difficulty in trying to group a bunch of Shapes together when we only have the reference to the Shape object. Some of the workarounds include trying to loop through all the shapes in the slide, selecting one by one, which is pretty inefficient and results in lengthy code.

A quick and easy way we found is to extract a ShapeRange object from the slide based on the names of the shapes.

string[] names = new string[] { shape1.Name, shape2.Name };
Shape group = this.GetCurrentSlide().Shapes.Range(names).Group();

Will be good to add this into our "Common add-in development traps" document for future contributors to take note!