terraform: add validate (#3946)

Co-authored-by: Starbeamrainbowlabs <sbrl@starbeamrainbowlabs.com>

pages/common/terraform.md

@@ -7,6 +7,10 @@
 
 `terraform init`
 
+- Verify that the configuration files are syntactically valid:
+
+`terraform validate`
+
 - Format configuration according to Terraform language style conventions:
 
 `terraform fmt`