add desc to schema for google_container_cluster

[edwardmedia]

Part of hashicorp/terraform-provider-google#6105

Release Note Template for Downstream PRs (will be copied)

[modular-magician]

Hi! I'm the modular magician. Your PR generated some diffs in downstreams - here they are.

Diff report:

Terraform GA: Diff ( 1 file changed, 262 insertions(+), 177 deletions(-))
Terraform Beta: Diff ( 1 file changed, 293 insertions(+), 191 deletions(-))

[modular-magician]

Hello! I am a robot who works on Magic Modules PRs.

I have detected that you are a community contributor, so your PR will be assigned to someone with a commit-bit on this repo for initial review.

Thanks for your contribution! A human will be with you soon.

@danawillow, please review this PR or find an appropriate assignee.

[modular-magician]

Hi! I'm the modular magician. Your PR generated some diffs in downstreams - here they are.

Diff report:

Terraform GA: Diff ( 1 file changed, 261 insertions(+), 177 deletions(-))
Terraform Beta: Diff ( 1 file changed, 292 insertions(+), 191 deletions(-))

[googlebot]

We found a Contributor License Agreement for you (the sender of this pull request), but were unable to determine that you authored the commits in this PR. Maybe you used a different email address in the git commits than was used to sign the CLA? If someone else authored these commits, then please add them to this pull request and have them confirm that they're okay with them being contributed to Google. If there are co-authors, make sure they're formatted properly.

In order to pass this check, please resolve this problem and then comment@googlebot I fixed it... If the bot doesn't comment, it means it doesn't think anything has changed.

ℹ️ Googlers: Go here for more info.

[modular-magician]

Hello! I am a robot who works on Magic Modules PRs.

I have detected that you are a community contributor, so your PR will be assigned to someone with a commit-bit on this repo for initial review.

Thanks for your contribution! A human will be with you soon.

@danawillow, please review this PR or find an appropriate assignee.

[googlebot]

CLAs look good, thanks!

ℹ️ Googlers: Go here for more info.

[modular-magician]

Hello! I am a robot who works on Magic Modules PRs.

I have detected that you are a community contributor, so your PR will be assigned to someone with a commit-bit on this repo for initial review.

Thanks for your contribution! A human will be with you soon.

@emilymye, please review this PR or find an appropriate assignee.

[modular-magician]

Hi! I'm the modular magician. Your PR generated some diffs in downstreams - here they are.

Diff report:

Terraform GA: Diff ( 1 file changed, 268 insertions(+), 181 deletions(-))
Terraform Beta: Diff ( 1 file changed, 292 insertions(+), 190 deletions(-))