update relese note for v2.2.0 (#3474)
update relese note for v2.2.0 (#3474)


GuangweiWang/openh264,cisco/openh264,GuangweiWang/openh264,GuangweiWang/openh264,cisco/openh264,cisco/openh264,cisco/openh264,mstorsjo/openh264,GuangweiWang/openh264,mstorsjo/openh264,cisco/openh264,GuangweiWang/openh264,GuangweiWang/openh264,cisco/openh264,mstorsjo/openh264,cisco/openh264,mstorsjo/openh264,mstorsjo/openh264,GuangweiWang/openh264,mstorsjo/openh264,mstorsjo/openh264