Add docs for High Performance OpenDAL

[Xuanwo]

OpenDAL offers numerous features, but some of them come with additional costs that may not be suitable for all cases. Therefore, OpenDAL allows users to make the decision themselves.

We can collect them and provide a guide for High Performance OpenDAL for users to tune their applications.

For example:

• Enable op.writer_with().buffer(buffer) for small writes
• Enable op.reader_with().buffer(buffer) for small reads
• Enable op.writer_with().concurrent(n) for concurrent wirtes.
• Enable feature trust_dns for async dns query & cache.
• List with metakey for reusing metadata during list.

[Xuanwo]

Another good example: https://github.com/GreptimeTeam/greptimedb/pull/4520

[Xuanwo]

I believe we can have a section in opendal::docs for this.