serviceusage api added in the default activate_apis (#10)

[bdelv]

Just adds serviceusage.googleapis.com in the default activated apis.

issue #10

Note: I still have an issue for the tests to all pass with linking the billing account but I don't think it is any relevant to this change.

[morgante]

Thanks! Please regenerate docs, as per contributing guide.

[bdelv]

It doesn't seem to change any README

➜  terraform-google-bootstrap git:(serviceusage-api-default) make docker_generate_docs
docker run --rm -it \
		-v /Users/brice/dev/temp/terraform-google-bootstrap:/workspace \
		gcr.io/cloud-foundation-cicd/cft/developer-tools:0.6.0 \
		/bin/bash -c 'source /usr/local/bin/task_helper_functions.sh && generate_docs'
Generating markdown docs with terraform-docs
Working in . ...
Success!
Working in ./examples/cloudbuild_enabled ...
Success!
Working in ./examples/simple ...
Success!
Working in ./modules/cloudbuild ...
Success!
Skipping ./test/fixtures/cloudbuild_enabled because README.md does not exist.
Skipping ./test/fixtures/simple because README.md does not exist.
Skipping ./test/setup because README.md does not exist.
➜  terraform-google-bootstrap git:(serviceusage-api-default) git status
On branch serviceusage-api-default
Your branch is up to date with 'origin/serviceusage-api-default'.

nothing to commit, working tree clean

It seems like the default values are not displayed for lists and maps in the generated docs

| Name | Description | Type | Default | Required |
| activate\_apis | List of APIs to enable in the seed project. | list(string) | `<list>` | no |

[morgante]

Thanks for the contribution, CI errors look spurious/unrelated.