(decedent had executed two wills during life and the second will was admitted to probate; more than two years after will admitted to probate, decedent's niece sued to set aside the will and probate the first will; two-year statute of limitations on such actions triggered on date of admission of will to probate and not when executor served niece with original petition to recover estate assets (which was the time the niece learned of the existence of the second will and that it had been admitted to probate); discovery rule inapplicable to will contest actions unless fraud or forgery present; court noted that probate records are public and all persons on constructive notice if they have any intent to contest the will; unawareness of probate proceedings does not impact statute of limitations).