Add TUTORIAL and FAQ in Sedna's Documentation

[Lj1ang]

What would you like to be documented:

• TUTORIAL: instructs users to customize their own cases.
• FAQ: records frequently asked questions and corresponding solutions.

Why is this needed: At present, Sedna's documentation doesn't teach users how to use Sedna very well. INTRODUCTION part tells about how Sedna's features are developed and EXAMPLE part is about how to quickly run the examples provided in Sedna. Neither of the two parts instructs users to customize their own cases based on Sedna's API.

[MooreZheng]

As mentioned, EXAMPLE part is about how to quickly run the examples provided in Sedna. It is important to have documents for further developing examples. /assign @luosiqi might help to follow up the issue.

[Lj1ang]

/assign @luosiqi

[kubeedge-bot]

@Lj1ang: GitHub didn't allow me to assign the following users: luosiqi.

Note that only kubeedge members, repo collaborators and people who have commented on this issue/PR can be assigned. Additionally, issues/PRs can only have 10 assignees at the same time. For more information please see the contributor guide

In response to [this](https://github.com/kubeedge/sedna/issues/390#issuecomment-1414843017): >/assign @luosiqi Instructions for interacting with me using PR comments are available [here](https://git.k8s.io/community/contributors/guide/pull-requests.md). If you have questions or suggestions related to my behavior, please file an issue against the [kubernetes/test-infra](https://github.com/kubernetes/test-infra/issues/new?title=Prow%20issue:) repository.

[MooreZheng]

hi @luosiqi pls also follow up this issue

[MooreZheng]

We have wonderful contributors working on these issues. @luosiqi https://github.com/kubeedge/sedna/pull/391 Proposal and tutorial of unstructured lifelong learning @qxygxt https://github.com/kubeedge/sedna/pull/401 Tutorial for ATCII Lifelong Learning Job