docs: update the branch name from master to main in contribution.…

…md (#5359)


#### What type of PR is this?
/kind documentation


#### What this PR does / why we need it:

Prevent code contributors from being misled by outdated documentation(1.x).

#### Which issue(s) this PR fixes:

Fixes #5358

#### Special notes for your reviewer:


#### Does this PR introduce a user-facing change?


```release-note
NONE
```

.github/pull_request_template.md

@@ -1,6 +1,6 @@
 <!--  Thanks for sending a pull request!  Here are some tips for you:
-1. 如果这是你的第一次，请阅读我们的贡献指南：<https://github.com/halo-dev/halo/blob/master/CONTRIBUTING.md>。
-1. If this is your first time, please read our contributor guidelines: <https://github.com/halo-dev/halo/blob/master/CONTRIBUTING.md>.
+1. 如果这是你的第一次，请阅读我们的贡献指南：<https://github.com/halo-dev/halo/blob/main/CONTRIBUTING.md>。
+1. If this is your first time, please read our contributor guidelines: <https://github.com/halo-dev/halo/blob/main/CONTRIBUTING.md>.
 2. 请根据你解决问题的类型为 Pull Request 添加合适的标签。
 2. Please label this pull request according to what type of issue you are addressing, especially if this is a release targeted pull request.
 3. 请确保你已经添加并运行了适当的测试。

CONTRIBUTING.md

@@ -34,7 +34,7 @@ git push origin {BRANCH_NAME}
 
 #### 5. 提交 pull request
 
-回到自己的仓库页面，选择 `New pull request` 按钮，创建 `Pull request` 到原仓库的 `master` 分支。
+回到自己的仓库页面，选择 `New pull request` 按钮，创建 `Pull request` 到原仓库的 `main` 分支。
 
 然后等待我们 Review 即可，如有 `Change Request`，再本地修改之后再次提交即可。
 
@@ -43,7 +43,7 @@ git push origin {BRANCH_NAME}
 ```bash
 git remote add upstream [email protected]:halo-dev/halo.git
 
-git pull upstream master
+git pull upstream main
 
 git push
 ```

README.md

@@ -60,7 +60,7 @@ Halo 使用 GPL-v3.0 协议开源，请遵守开源协议。
 
 ## 贡献
 
-参考 [CONTRIBUTING](https://github.com/halo-dev/halo/blob/master/CONTRIBUTING.md)。
+参考 [CONTRIBUTING](https://github.com/halo-dev/halo/blob/main/CONTRIBUTING.md)。
 
 <a href="https://github.com/halo-dev/halo/graphs/contributors"><img src="https://opencollective.com/halo/contributors.svg?width=890&button=false" /></a>