cef.redist.x64 is missing NuGet package README file

We've noticed that your package on NuGet.org is missing a README file.

## Why READMEs are Important
Our customer research indicates that one of the top problems that package consumers face is insufficient package documentation such as README files. Adding a README file to your package will help users quickly understand what the package is and what it does. Since your README will be the first impression for users when they view your package on NuGet.org, it is crucial for authors to write and include high-quality READMEs for their packages.

## Get Started with READMEs

### How to Add a README
If you're new to NuGet READMEs, follow guidance on [how to add one to your package](https://devblogs.microsoft.com/nuget/add-a-readme-to-your-nuget-package/).

### How to write high quality of READMEs
Follow [a blog post](https://devblogs.microsoft.com/nuget/write-a-high-quality-readme-for-nuget-packages/) with README best practices and a template file to help you get started.

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Thank you for your contribution to the NuGet community.

从仓库的打包工作流以及 issue 中链接的 NuGet README 指南开始。为 cef.redist.x64 包添加合适的 README，并验证发布时生成的 NuGet 包包含该文件。

由索引模型根据 Issue 内容生成。