fix(docs): update documentation links

Author: baprx

README.md

@@ -42,7 +42,7 @@ Current version is 12.0. Upgrade guides:
 ```HCL
 module "gce-lb-http" {
   source            = "GoogleCloudPlatform/lb-http/google"
-  version           = "~> 9.0"
+  version           = "~> 12.0"
 
   project           = "my-project-id"
   name              = "group-http-lb"

autogen/README.md

@@ -45,13 +45,13 @@ intended for Terraform 0.12.x is [v4.5.0](https://registry.terraform.io/modules/
 
 Current version is 12.0. 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)
-- [10.X -> 11.0](/docs/upgrading_to_v11.0.md)
+- [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
 
@@ -62,7 +62,7 @@ module "gce-lb-http" {
 module "lb-http" {
 {% endif %}
   source            = "GoogleCloudPlatform/lb-http/google{{ module_path }}"
-  version           = "~> 9.0"
+  version           = "~> 12.0"
 
   project           = "my-project-id"
   {% if serverless %}