Federal Reserve Chair Janet Yellen said Wednesday that the Fed is committed to making sure that the regulations it imposes on the nation’s community banks are not overly burdensome, noting a proposed rule issued last week to simplify requirements governing how much capital these banks must hold.   In remarks to a community banking conference in St. Louis, Yellen said the proposed new rule on capital requirements was the latest effort by regulators to ease burdens on smaller banks. She says the Fed is seeking to increase the number of …