docs: change image.history() return type to list (#3076)

[Khushiyant]

Fix #3076
As mentioned in docs here, it should return str but it returns the history as list object

Currently:

history()
Show the history of an image.

Returns:
The history of the image.

Return type:
(str)

Raises:
docker.errors.APIError – If the server returns an error.

Update:

history()
Show the history of an image.

Returns:
The history of the image.

Return type:
(list)

Raises:
docker.errors.APIError – If the server returns an error.

For examples:

Basic alpine image return below history as list

[{'Comment': '', 'Created': 1701999570, 'CreatedBy': '/bin/sh -c #(nop) CMD ["/bin/sh"]', 'Id': 'sha256:<SHA>', 'Size': 0, 'Tags': ['alpine:latest']}, {'Comment': '', 'Created': 1701999570, 'CreatedBy': '/bin/sh -c #(nop) ADD file:<file> in / ', 'Id': '<missing>', 'Size': 7728526, 'Tags': None}]

[Khushiyant]

@milas PTAL

[milas]

LGTM, thanks!