provider/gitlab: Documentation improvements (#14824)

* provider/gitlab: Fix documentation copypasta

The original provider and docs were copied from the github provider, one
bit of copy paste slipped unmissed.

* provider/gitlab: Document `gitlab_project#id`

* provider/gitlab: Document `gitlab_project#namespace_id`

* provider/gitlab: Add fuller demonstration to the provider page

Following in the style of other provider pages, add a worked example
showing off all of the available resources offered by the gitlab
provider.

* provider/gitlab: Correct sample for gitlab_project

website/source/docs/providers/gitlab/index.html.markdown

@@ -23,9 +23,35 @@ provider "gitlab" {
     token = "${var.gitlab_token}"
 }
 
-# Add a project to the organization
+# Add a project owned by the user
 resource "gitlab_project" "sample_project" {
-    ...
+    name = "example"
+}
+
+# Add a hook to the project
+resource "gitlab_project_hook" "sample_project_hook" {
+    project = "${gitlab_project.sample_project.id}"
+    url = "https://example.com/project_hook"
+}
+
+# Add a deploy key to the project
+resource "gitlab_deploy_key" "sample_deploy_key" {
+    project = "${gitlab_project.sample_project.id}"
+    title = "terraform example"
+    key = "ssh-rsa AAAA..."
+}
+
+# Add a group
+resource "gitlab_group" "sample_group" {
+    name = "example"
+    path = "example"
+    description = "An example group"
+}
+
+# Add a project to the group - example/example
+resource "gitlab_project" "sample_group_project" {
+    name = "example"
+    namespace_id = "${gitlab_group.sample_group.id}"
 }
 ```
 

website/source/docs/providers/gitlab/r/project.html.markdown

@@ -3,7 +3,7 @@ layout: "gitlab"
 page_title: "GitLab: gitlab_project"
 sidebar_current: "docs-gitlab-resource-project-x"
 description: |-
-  Creates and manages projects within Github organizations
+  Creates and manages projects within Gitlab
 ---
 
 # gitlab\_project
@@ -15,11 +15,11 @@ GitLab organization.
 ## Example Usage
 
 ```hcl
-resource "gitlab_repository" "example" {
+resource "gitlab_project" "example" {
   name        = "example"
   description = "My awesome codebase"
 
-  visbility_level = "public"
+  visibility_level = "public"
 }
 ```
 
@@ -31,6 +31,9 @@ The following arguments are supported:
 
 * `description` - (Optional) A description of the project.
 
+* `namespace_id` - (Optional) The namespace to create this project in.
+  See [`gitlab_group`](group.html) for an example.
+
 * `default_branch` - (Optional) The default branch for the project.
 
 * `issues_enabled` - (Optional) Enable issue tracking for the project.
@@ -49,6 +52,8 @@ The following arguments are supported:
 
 The following additional attributes are exported:
 
+* `id` - Integer that uniquely identifies the project within the gitlab install.
+
 * `ssh_url_to_repo` - URL that can be provided to `git clone` to clone the
   repository via SSH.