Adds a new annotation to the collection. Returns a PdfAnnot object
representing the newly created annotation.
Contents specifies the annotation contents, such as
text displayed in a pop-up window when the annotation is opened.
Param is a parameter object or parameter string
specifying the annotation type and other parameters.
Name specifies annotation-specific information
Path specifies a file path to be used with FileAttachment
annotations and is ignored by all other annotation types.
The Add method is described in detail in Section 10.3.2 - Add Method Parameters.
Usage:
PdfAnnot objAnnot = objPage.Annots.Add("Hello world", "type=text;x=10;y=400;width=100;height=50");
