Add github-pages template

[vim90]

This is a PR for github-pages

After the repo merged, please enable github-pages by:

1. Goto Repo
2. Setting -> Pages -> Branch
3. Select 'master' branch and '/docs' directory
4. Press 'Save'

Here is an example link on my fork: https://shawnvim.github.io/langchain-ChatGLM/

You can get your own URL by replace the user name from 'shawnvim' to “ imClumsyPanda' when Environment build is finished.

[imClumsyPanda]

这个 PR 先放放，晚点我在你基础上 commit 一下再 merge 好了