add migration guide

guides/MIGRATION_GUIDE_v1_to_v2.md

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+# Migration Guide for ROSA Module
+
+## Key Changes
+
+In the latest update to the ROSA module, there are significant modifications affecting how the module integrates with Red Hat's infrastructure and manages its resources.
+
+### Removed variables
+
+- **offline_access_token**: This variable has been removed.
+- **url**: This variable, which previously defined the Red Hat Console URI, has also been removed.
+
+### New Variables
+
+The functionality provided by the removed parameters has been replaced by:
+- **RHCS_TOKEN**: Used to provide authentication for Red Hat Cloud Services.
+- **RHCS_URL**: Specifies the URL for Red Hat Cloud Services.
+
+### Provider Management
+
+- The ROSA module no longer includes an embedded provider configuration.
+- Users must now explicitly define the provider.
+- An example provider configuration can be found in `modules/fixtures/backend.tf`.
+
+### Migration Path
+
+To upgrade to the latest version of the ROSA module:
+1. **Update Your Variables**:
+   - Replace `offline_access_token` with `RHCS_TOKEN`.
+   - Replace `url` with `RHCS_URL`.
+
+2. **Define the Provider**: Add the provider configuration explicitly in your Terraform code by referencing the example in `modules/fixtures/backend.tf`.
+
+3. **Verify Integration**: Ensure the new variables are properly set and verify that the ROSA module is correctly communicating with Red Hat Cloud Services.