Apache SkyWalking WebSite Deployment Process Migration

["kezhenxu94@apache" <ke...@apache.org>]

Hi all

I have just drafted a pull request [1] to set up a GitHub Action workflow to automate the deployment process. 

We previously used travis-ci, a third-party platform to automatically deploy our website, by configuring a personal GitHub token (with write access) there, which is extremely dangerous in terms of security and IP, and should have not been allowed by ASF policy. 

All PMC members and committers, please take care of your accounts and note that:

1. Individual contributions MUST come from human, don’t use your personal tokens to build a bot or anything similar, or delegate your permissions to any third-party platform.
2. If needed, automated commits MUST be approved by Infra before it happens.

Therefore, I migrated the deployment process to GitHub Actions, which doesn’t require secrets/tokens. As there are projects [2] using this kind of deployment process for a long time, I think it’s approved by Infra already, otherwise, @infra please let us know.

[1] https://github.com/apache/skywalking-website/pull/144
[2] https://github.com/apache/incubator-weex-site/blob/master/.github/workflows/main.yml

————————— 
Zhenxu Ke (柯振旭)
GitHub @kezhenxu94