chore: update docs (#473)

Author: complexsplit

README.md

@@ -27,14 +27,15 @@ intended for Terraform 0.12.x is [v4.5.0](https://registry.terraform.io/modules/
 
 ## Version
 
-Current version is 9.0. Upgrade guides:
-
-- [2.X -> 3.0](/docs/upgrading-v2.0.0-v3.0.0.md)
-- [3.X -> 4.0](/docs/upgrading_to_v4.0.md)
-- [6.X -> 7.0](/docs/upgrading_to_v7.0.md)
-- [7.X -> 8.0](/docs/upgrading_to_v8.0.md)
-- [8.X -> 9.0](/docs/upgrading_to_v9.0.md)
-- [9.X -> 10.0](/docs/upgrading_to_v10.0.md)
+Current version is 12.0. Upgrade guides:
+
+- [2.X -> 3.0](https://github.com/terraform-google-modules/terraform-google-lb-http/blob/master/docs/upgrading_to_v3.0.0.md)
+- [3.X -> 4.0](https://github.com/terraform-google-modules/terraform-google-lb-http/blob/master/docs/upgrading_to_v4.0.md)
+- [6.X -> 7.0](https://github.com/terraform-google-modules/terraform-google-lb-http/blob/master/docs/upgrading_to_v7.0.md)
+- [7.X -> 8.0](https://github.com/terraform-google-modules/terraform-google-lb-http/blob/master/docs/upgrading_to_v8.0.md)
+- [8.X -> 9.0](https://github.com/terraform-google-modules/terraform-google-lb-http/blob/master/docs/upgrading_to_v9.0.md)
+- [9.X -> 10.0](https://github.com/terraform-google-modules/terraform-google-lb-http/blob/master/docs/upgrading_to_v10.0.md)
+- [10.X -> 11.0](https://github.com/terraform-google-modules/terraform-google-lb-http/blob/master/docs/upgrading_to_v11.0.md)
 
 ## Usage