docs on setting up vdb-config in an automated setting

[nick-youngblut]

The docs at https://github.com/ncbi/sra-tools/wiki/05.-Toolkit-Configuration assume an interactive setup. For pipelines, especially containerized pipelines, it would be helpful to have more documentation on non-interactive setups (e.g., creating custom configs in a Dockerfile for accepting AWS or GCP charges).

[nick-youngblut]

Also, https://github.com/ncbi/sra-tools/blob/master/README-vdb-config refer to ngc files:

The "import dbGaP-project" button presents you with another dialog to select
a ngc-file

...but do not actually state what an ngc file actually is.