update release note (#3726)

update release note (#3703)

update release note (#3575)

update release note (#3539)

update relese note for v2.2.0 (#3474)

Merge pull request #3285 from GuangweiWang/public-release-2.1.1

change release note for openh264v2.1.1

Merge pull request #3243 from ycqian/v2.1.0

update v2.1.0 ReleasNote to openh264v2.1.0 branch

Merge pull request #3132 from aiszhang/public-release-update-version-…

…2.0.0

update version to 2.0.0

Merge pull request #2984 from GuangweiWang/public-release-update-vers…

…ion1.8.0

add download URLs for openh264v1.8.0 binaries

Merge pull request #2767 from ruil2/add_link1.7

add v1.7 release notes