use cases based on OpenMLDB

[lumianph]

We are calling the community for the contribution to help build more use cases based on OpenMLDB. The use cases can be machine learning applications, as well as other cool stuffs from your idea :-)

You may refer to our existing use cases for reference. https://openmldb.ai/docs/en/main/use_case/index.html https://openmldb.ai/docs/zh/main/use_case/index.html