[Docs] Container Contract: Example is wrong

[anbrsap]

pipeline/docs/container-contract.md

Lines 40 to 43 in 23b3dee

	For example, consider the following `Task`, which uses two images named
	`gcr.io/cloud-builders/gcloud` and `gcr.io/cloud-builders/docker`. In this example, the
	Pipelines controller retrieves the `entrypoint` value from the registry, which allows
	the `Task` to execute the `gcloud` and `docker` commands, respectively.

Retrieving the entrypoint from the registry happens only if no command is specified. But in the example below command is specified and therefore the entrypoint is not retrieved from the registry.

pipeline/docs/container-contract.md

Lines 45 to 52 in 23b3dee

	```yaml
	spec:
	steps:
	- image: gcr.io/cloud-builders/gcloud
	command: [gcloud]
	- image: gcr.io/cloud-builders/docker
	command: [docker]
	```