docs: add GCP SEV-SNP reference

docs/docs/overview/clouds.md

@@ -5,7 +5,7 @@ What works on which cloud? Currently, Confidential VMs (CVMs) are available in v
 For Constellation, the ideal environment provides the following:
 
 1. Ability to run arbitrary software and images inside CVMs
-2. CVMs based on AMD SEV-SNP (available in EPYC CPUs since the Milan generation) or Intel TDX (available in Xeon CPUs since the Sapphire Rapids generation)
+2. CVMs based on AMD SEV-SNP (available in EPYC CPUs since the Milan generation) or Intel TDX (available in Xeon CPUs since the Sapphire Rapid generation)
 3. Ability for CVM guests to obtain raw hardware attestation statements
 4. Reviewable, open-source firmware inside CVMs
 5. Capability of the firmware to attest the integrity of the code it passes control to, e.g., with an embedded virtual TPM (vTPM)

docs/docs/reference/cli.md

@@ -78,7 +78,7 @@ constellation config generate {aws|azure|gcp|openstack|qemu|stackit} [flags]
 ### Options
 
 ```
-  -a, --attestation string   attestation variant to use {aws-sev-snp|aws-nitro-tpm|azure-sev-snp|azure-tdx|azure-trustedlaunch|gcp-sev-snp|gcp-sev-es|qemu-vtpm}. If not specified, the default for the cloud provider is used
+  -a, --attestation string   attestation variant to use {aws-sev-snp|aws-nitro-tpm|azure-sev-snp|azure-tdx|azure-trustedlaunch|gcp-sev-es|gcp-sev-snp|qemu-vtpm}. If not specified, the default for the cloud provider is used
   -h, --help                 help for generate
   -k, --kubernetes string    Kubernetes version to use in format MAJOR.MINOR (default "v1.28")
 ```

terraform-provider-constellation/docs/data-sources/attestation.md

@@ -33,6 +33,7 @@ data "constellation_attestation" "test" {
   * `azure-sev-snp`
   * `azure-tdx`
   * `gcp-sev-es`
+  * `gcp-sev-snp`
   * `qemu-vtpm`
 - `csp` (String) CSP (Cloud Service Provider) to use. (e.g. `azure`)
 See the [full list of CSPs](https://docs.edgeless.systems/constellation/overview/clouds) that Constellation supports.
@@ -83,6 +84,7 @@ Read-Only:
   * `azure-sev-snp`
   * `azure-tdx`
   * `gcp-sev-es`
+  * `gcp-sev-snp`
   * `qemu-vtpm`
 
 <a id="nestedatt--attestation--azure_firmware_signer_config"></a>

terraform-provider-constellation/docs/data-sources/image.md

@@ -32,6 +32,7 @@ data "constellation_image" "example" {
   * `azure-sev-snp`
   * `azure-tdx`
   * `gcp-sev-es`
+  * `gcp-sev-snp`
   * `qemu-vtpm`
 - `csp` (String) CSP (Cloud Service Provider) to use. (e.g. `azure`)
 See the [full list of CSPs](https://docs.edgeless.systems/constellation/overview/clouds) that Constellation supports.

terraform-provider-constellation/docs/resources/cluster.md

@@ -111,6 +111,7 @@ Required:
   * `azure-sev-snp`
   * `azure-tdx`
   * `gcp-sev-es`
+  * `gcp-sev-snp`
   * `qemu-vtpm`
 
 Optional: