Update README.md

[ctyytc]

Ⅰ. Describe what this PR did

1. 区分c++和golang插件文档地址
2. 修正golang插件目录链接的文字表述

Ⅱ. Does this pull request fix one issue?

无

Ⅲ. Why don't you add test cases (unit test/integration test)?

只是修改了文档，无需测试

Ⅳ. Describe how to verify it

只是修改了文档

Ⅴ. Special notes for reviews

无

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}

[johnlanni]

@ctyytc Thanks! Please sign the CLA.

[johnlanni]

Thanks