Move `lib9c.js` docs as lib9c docs' parts

[moreal]

Context

There is a /@planetarium/lib9c/docs directory which contains documentation about lib9c.js. And we distributed it as lib9c.nine-chronicles.dev.

But since #2815, lib9c.nine-chronicles.dev has been replaced by the DocFx documentation. However, it still needs to provide lib9c.js documentation.

Overview

So the files under @planetarium/lib9c/docs should be moved to under the docs/integrations/javascript directory (this directory may need to be created). Also it should update toc.yaml files too.