api: swagger: add IPAMConfig on IPAM

[fussybeaver]

Signed-off-by: Niel Drummond niel@drummond.lu

fixes #43292
ref: fussybeaver/bollard#201

- What I did
Changed the swagger documentation signature for the IPAM Config field from an array of strings, to a new IPAMConfig type.

- How I did it
Amended the YAML documentation for version 1.41.

- How to verify it
I used a swagger generator on the new type to verify the yaml and new type are created. Testing executed with the newly generated codebase by the original issue owner.

- Description for the changelog

Changed swagger documentation IPAM config from array to IPAMConfig type

- A picture of a cute animal (not mandatory but encouraged)

[thaJeztah]

Thanks for contributing! I see this PR is updating the swagger file for v1.41 in the docs directory; could you add a commit that updates the swagger file inside the API directory as well? https://github.com/moby/moby/blob/master/api/swagger.yaml

The file inside the API directory is the one that's used to generate (some of) the API code, and (on the main/master branch) is used for the upcoming v1.42 API.

For these, it's good to keep them as separate commits (in case we want to cherry-pick to the 20.10 release branch, in which cause we could decide to only backport the docs changes).

[fussybeaver]

Thanks for checking. I've added a new commit for the swagger.yaml and reworded the commit lines.

[thaJeztah]

LGTM, thanks!!