Improve SEO for new website

[ShadowySpirits]

Please do not create a Pull Request without creating an issue first.

What is the purpose of the change

Now we have a new website, but its links don't work with the old website. So old site links on search engines will cause 404. We can google for site:rocketmq.apache.org to verify it, only the home page is accessible in the top results.

I propose to maintain compatibility with old site links to optimize SEO. There are two ways to do this:

1. make the new website links as same as the old one
2. set 301 redirects to route traffic from an old path to a new URL

Moreover, URLs on the new website look weird. Maybe better to use slug.

https://rocketmq.apache.org/docs/%E4%BB%8B%E7%BB%8D/03whatis
-> https://rocketmq.apache.org/docs/what-is-rocketmq

[tsunghanjacktsai]

Hi @ShadowySpirits ,

Thx for your suggesstion. We've now corrected those links from the old official website and redirected them to the new one, please have a look now. You could inspect the broken links that could be found with search engines, and help us redirect them to the appropriate one here (just add it to the list as the others): https://github.com/apache/rocketmq-site/blob/8a26235282f9e6b3713bc54b998eb617697b12bb/docusaurus.config.js#L124

[ShadowySpirits]

@tsunghanjacktsai I have submitted a pr #227, please have a look.