resource/gitlab_project_variable: Improve documentation and reference upstream docs

Author: timofurrer

docs/resources/project_variable.md

@@ -3,25 +3,18 @@
 page_title: "gitlab_project_variable Resource - terraform-provider-gitlab"
 subcategory: ""
 description: |-
-  This resource allows you to create and manage CI/CD variables for your GitLab projects.
-  For further information on variables, consult the gitlab
-  documentation https://docs.gitlab.com/ce/ci/variables/README.html#variables.
-  ~> Important: If your GitLab version is older than 13.4, you may see nondeterministic behavior
-  when updating or deleting gitlab_project_variable resources with non-unique keys, for example if
-  there is another variable with the same key and different environment scope. See
-  this GitLab issue https://gitlab.com/gitlab-org/gitlab/-/issues/9912.
+  The gitlab_project_variable resource allows to manage the lifecycle of a CI/CD variable for a project.
+  ~> Important: If your GitLab version is older than 13.4, you may see nondeterministic behavior when updating or deleting gitlabprojectvariable resources with non-unique keys, for example if there is another variable with the same key and different environment scope. See this GitLab issue https://gitlab.com/gitlab-org/gitlab/-/issues/9912.
+  Upstream API: GitLab REST API docs https://docs.gitlab.com/ee/api/project_level_variables.html
 ---
 
 # gitlab_project_variable (Resource)
 
-This resource allows you to create and manage CI/CD variables for your GitLab projects.
-For further information on variables, consult the [gitlab
-documentation](https://docs.gitlab.com/ce/ci/variables/README.html#variables).
+The `gitlab_project_variable` resource allows to manage the lifecycle of a CI/CD variable for a project.
 
-~> **Important:** If your GitLab version is older than 13.4, you may see nondeterministic behavior
-when updating or deleting `gitlab_project_variable` resources with non-unique keys, for example if
-there is another variable with the same key and different environment scope. See
-[this GitLab issue](https://gitlab.com/gitlab-org/gitlab/-/issues/9912).
+~> **Important:** If your GitLab version is older than 13.4, you may see nondeterministic behavior when updating or deleting gitlab_project_variable resources with non-unique keys, for example if there is another variable with the same key and different environment scope. See [this GitLab issue](https://gitlab.com/gitlab-org/gitlab/-/issues/9912).
+
+**Upstream API**: [GitLab REST API docs](https://docs.gitlab.com/ee/api/project_level_variables.html)
 
 ## Example Usage
 

internal/provider/resource_gitlab_project_variable.go

@@ -13,13 +13,11 @@ import (
 
 var _ = registerResource("gitlab_project_variable", func() *schema.Resource {
 	return &schema.Resource{
-		Description: "This resource allows you to create and manage CI/CD variables for your GitLab projects.\n" +
-			"For further information on variables, consult the [gitlab\n" +
-			"documentation](https://docs.gitlab.com/ce/ci/variables/README.html#variables).\n\n" +
-			"~> **Important:** If your GitLab version is older than 13.4, you may see nondeterministic behavior\n" +
-			"when updating or deleting `gitlab_project_variable` resources with non-unique keys, for example if\n" +
-			"there is another variable with the same key and different environment scope. See\n" +
-			"[this GitLab issue](https://gitlab.com/gitlab-org/gitlab/-/issues/9912).",
+		Description: `The ` + "`" + `gitlab_project_variable` + "`" + ` resource allows to manage the lifecycle of a CI/CD variable for a project.
+
+~> **Important:** If your GitLab version is older than 13.4, you may see nondeterministic behavior when updating or deleting gitlab_project_variable resources with non-unique keys, for example if there is another variable with the same key and different environment scope. See [this GitLab issue](https://gitlab.com/gitlab-org/gitlab/-/issues/9912).
+
+**Upstream API**: [GitLab REST API docs](https://docs.gitlab.com/ee/api/project_level_variables.html)`,
 
 		CreateContext: resourceGitlabProjectVariableCreate,
 		ReadContext:   resourceGitlabProjectVariableRead,