storage: fix typo in docs
storage: fix typo in docs

Change-Id: I3efd9fc7a7e232a47b09391e5beb6238d0a301a5
Reviewed-on: https://code-review.googlesource.com/c/36433
Reviewed-by: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>
Reviewed-by: Eno Compton <ad9228447a2ef39a5712f4b80b45071fa843fa0d@google.com>

googleapis/google-cloud-go,googleapis/google-cloud-go,googleapis/google-cloud-go,googleapis/google-cloud-go