What happens?

在沙盒环境样式隔离的环境下。子应用document. getElementById 等API因为应用在shadowDOM里面。所以没有办法获取正确数据。建议对document.getElementById等 做打补丁处理（先在shadowDOM查询然后在去document上查询），才能达到子应用完全技术隔离。

A clear and concise description of what the bug is.

Mini Showcase Repository(REQUIRED)

Provide a mini GitHub repository which can reproduce the issue.

https://github.com/umijs/qiankun/blob/v2.0.0/examples/main

Analogous to @feature-hub/react's FeatureAppLoader the feature-app-loader custom element should allow the integrator to pass a set of css file links.

Since both the feature-app-loader and feature-app-container have their own shadow DOM, we also need the same prop on the feature-app-container so it can inject the css link into its DOM.

General description

use slate to document scalecube

Given scalecube project
And doc.md file in the root of the project
And buildDoc.sh script under scripts folder
And slate project
When merging the branch to develop and bumping the version
Then the buildDoc.sh script is running 
And copy the doc.md file from scalecube to slate proj

• enhance response to caller with some standard headers identifying composer