Missing documentation about create_distributed_table_concurrently

Hey,

It looks like the documentation has no mention about `create_distributed_table_concurrently` which is really huge feature to make the citus migration smoother.

I discovered the feature by reading this article and I'm pretty sure lot of people are missing it because of the lack of documentation: https://www.citusdata.com/blog/2022/09/19/citus-11-1-shards-postgres-tables-without-interruption/