chore(docs): Add a note about region to S3 guide (#1509)

Author: JorTurFer

docs/guides/aws_provider_s3_stackit.md

@@ -7,6 +7,9 @@ page_title: "Using AWS Provider for STACKIT Object Storage (S3 compatible)"
 
 This guide outlines the process of utilizing the [AWS Terraform Provider](https://registry.terraform.io/providers/hashicorp/aws/latest/docs) alongside the STACKIT provider to create and manage STACKIT Object Storage (S3 compatible) resources.
 
+>Note: AWS Provider uses the `region` as cache key to manage the connection efficiently. Therefore, the `region` must be set to the desired one in all the resources explicitly to ensure proper functionality when multiple regions are used.
+
+
 ## Steps
 
 1. **Configure STACKIT Provider**
@@ -65,6 +68,7 @@ This guide outlines the process of utilizing the [AWS Terraform Provider](https:
 
    ```hcl
    resource "aws_s3_object" "test_file" {
+     region       = "eu01"
      bucket       = stackit_objectstorage_bucket.example.name
      key          = "hello_world.txt"
      source       = "files/hello_world.txt"
@@ -73,6 +77,7 @@ This guide outlines the process of utilizing the [AWS Terraform Provider](https:
    }
 
    resource "aws_s3_bucket_policy" "allow_public_read_access" {
+     region = "eu01"
      bucket = stackit_objectstorage_bucket.example.name
      policy = <<EOF
      {

templates/guides/aws_provider_s3_stackit.md.tmpl

@@ -7,6 +7,9 @@ page_title: "Using AWS Provider for STACKIT Object Storage (S3 compatible)"
 
 This guide outlines the process of utilizing the [AWS Terraform Provider](https://registry.terraform.io/providers/hashicorp/aws/latest/docs) alongside the STACKIT provider to create and manage STACKIT Object Storage (S3 compatible) resources.
 
+>Note: AWS Provider uses the `region` as cache key to manage the connection efficiently. Therefore, the `region` must be set to the desired one in all the resources explicitly to ensure proper functionality when multiple regions are used.
+
+
 ## Steps
 
 1. **Configure STACKIT Provider**
@@ -65,6 +68,7 @@ This guide outlines the process of utilizing the [AWS Terraform Provider](https:
 
    ```hcl
    resource "aws_s3_object" "test_file" {
+     region       = "eu01"
      bucket       = stackit_objectstorage_bucket.example.name
      key          = "hello_world.txt"
      source       = "files/hello_world.txt"
@@ -73,6 +77,7 @@ This guide outlines the process of utilizing the [AWS Terraform Provider](https:
    }
 
    resource "aws_s3_bucket_policy" "allow_public_read_access" {
+     region = "eu01"
      bucket = stackit_objectstorage_bucket.example.name
      policy = <<EOF
      {