docs(backend): fix s3 backend bucket name (#1984)

Author: quantumsheep

docs/index.md

@@ -230,7 +230,7 @@ Configure your backend as:
 ```
 terraform {
   backend "s3" {
-    bucket                      = "terraform_state"
+    bucket                      = "terraform-state"
     key                         = "my_state.tfstate"
     region                      = "fr-par"
     endpoint                    = "https://s3.fr-par.scw.cloud"