NEW YORK (Reuters) - Facebook's corporate governance rules, which give shareholders little say in how the social networking website would be run as a public company, are raising the hackles of one of the largest U.S. investors, the California State Teachers' Retirement System. The pension fund, which has a portfolio valued at around $145 billion, is planning to send a letter to Facebook, hoping to engage the social networking website on corporate governance, two CalSTRS executives told Reuters in an interview on Monday. ...