By Matt Tracy WASHINGTON (Reuters) -Google owner Alphabet is tapping the U.S. dollar and euro debt markets in a multi-tranche senior unsecured notes offering. The digital media and tech giant will use the proceeds from the note sale for general corporate purposes, including the potential repayment of a portion of its outstanding debt, according to a Monday report by Moody's Ratings. Alphabet last took out fresh debt in April, tapping the euro debt market for 6.75 billion euros ($7.87 billion) for the fi ...