Added English OpenHarmony-v3.1-release.md

Signed-off-by: Nwusongqing <wusongqing@huawei.com>

README.md

@@ -16,7 +16,7 @@ This repository stores device and application development documents provided by
 
  - master: the latest version.
 
- - OpenHarmony 3.1 Beta. [Learn more](en/release-notes/OpenHarmony-v3.1-beta.md)
+ - OpenHarmony 3.1 Release. [Learn more](en/release-notes/OpenHarmony-v3.1-release.md)
 
  - OpenHarmony 3.0 LTS. [Learn more](en/release-notes/OpenHarmony-v3.0-LTS.md)
 

en/release-notes/Readme.md

 # OpenHarmony Release Notes
 ## OpenHarmony 3.x Releases
--   [OpenHarmony 3.1 Beta (2021-12-31)](OpenHarmony-v3.1-beta.md)
--   [OpenHarmony 3.0.2 LTS (2022-01-12)](OpenHarmony-v3.0.2-LTS.md)
--   [OpenHarmony 3.0.1 LTS (2022-01-12)](OpenHarmony-v3.0.1-LTS.md)
--   [OpenHarmony 3.0 LTS (2021-09-30)](OpenHarmony-v3.0-LTS.md)
+-   [OpenHarmony v3.1 Release (2022-03-30)](OpenHarmony-v3.1-release.md)
+-   [OpenHarmony v3.1 Beta (2021-12-31)](OpenHarmony-v3.1-beta.md)
+-   [OpenHarmony v3.0.2 LTS (2022-03-18)](OpenHarmony-v3.0.2-LTS.md)
+-   [OpenHarmony v3.0.1 LTS (2022-01-12)](OpenHarmony-v3.0.1-LTS.md)
+-   [OpenHarmony v3.0 LTS (2021-09-30)](OpenHarmony-v3.0-LTS.md)
 
 ## OpenHarmony 2.x Releases
--   [OpenHarmony 2.2 beta2 (2021-08-04)](OpenHarmony-v2.2-beta2.md)
+
+-   [OpenHarmony v2.2 beta2 (2021-08-04)](OpenHarmony-v2.2-beta2.md)
 -   [OpenHarmony 2.0 Canary (2021-06-01)](OpenHarmony-2-0-Canary.md)
 ## OpenHarmony 1.x Releases
--   [OpenHarmony 1.1.4 LTS (2022-02-11)](OpenHarmony-v1-1-4-LTS.md)
--   [OpenHarmony 1.1.3 LTS (2021-09-30)](OpenHarmony-v1-1-3-LTS.md)
--   [OpenHarmony 1.1.2 LTS (2021-08-04)](OpenHarmony-v1.1.2-LTS.md)
+-   [OpenHarmony v1.1.4 LTS (2022-02-11)](OpenHarmony-v1-1-4-LTS.md)
+-   [OpenHarmony v1.1.3 LTS (2021-09-30)](OpenHarmony-v1-1-3-LTS.md)
+-   [OpenHarmony v1.1.2 LTS (2021-08-04)](OpenHarmony-v1.1.2-LTS.md)
 -   [OpenHarmony 1.1.1 LTS (2021-06-22)](OpenHarmony-1-1-1-LTS.md)
 -   [OpenHarmony 1.1.0 LTS (2021-04-01)](OpenHarmony-1-1-0-LTS.md)
 -   [OpenHarmony 1.0 (2020-09-10)](OpenHarmony-1-0.md)