Add tutorial & README

[k82cn]

We need to update tutorial & README accordingly for volcano.

[k82cn]

/assign @asifdxtreme

We need more doc about job management, please refer to https://github.com/volcano-sh/volcano/tree/master/docs/design

[k82cn]

please also update http://volcano.sh accordingly, including kube-batch's new doc, e.g. reclaim.

[asifdxtreme]

@k82cn okay, will add it accordingly

[asifdxtreme]

Relevant docs has been added via PR's volcano-sh/website#26 volcano-sh/website#23
@k82cn Do we need to add more docs to the website or we can go ahead and close this issue?

Current preview of the website is here https://asif-volcano.netlify.com/docs/