Make the purpose of artifact config options clearer

doc/ci/build_artifacts/README.md

 # Introduction to build artifacts
 
 Artifacts is a list of files and directories which are attached to a build
-after it completes successfully.
+after it completes successfully.  Artificats is enabled by default.  _If you are searching for ways to use artifacts, jump to
+[Defining artifacts in `.gitlab-ci.yml`](#defining-artifacts-in-gitlab-ciyml)._
 
 Since GitLab 8.2 and [GitLab Runner] 0.7.0, build artifacts that are created by
 GitLab Runner are uploaded to GitLab and are downloadable as a single archive
@@ -16,13 +17,9 @@ The artifacts browser will be available only for new artifacts that are sent
 to GitLab using GitLab Runner version 1.0 and up. It will not be possible to
 browse old artifacts already uploaded to GitLab.
 
-## Enabling build artifacts
-
-_If you are searching for ways to use artifacts, jump to
-[Defining artifacts in `.gitlab-ci.yml`](#defining-artifacts-in-gitlab-ciyml)._
+## Disabling build artifacts
 
-The artifacts feature is enabled by default in all GitLab installations.
-To disable it site-wide, follow the steps below.
+To disable artifacts site-wide, follow the steps below.
 
 ---
 
@@ -31,7 +28,7 @@ To disable it site-wide, follow the steps below.
 1. Edit `/etc/gitlab/gitlab.rb` and add the following line:
 
     ```ruby
-    gitlab_rails['artifacts_enabled'] = true
+    gitlab_rails['artifacts_enabled'] = false
     ```
 
 1. Save the file and [reconfigure GitLab][] for the changes to take effect.
@@ -44,7 +41,7 @@ To disable it site-wide, follow the steps below.
 
     ```yaml
     artifacts:
-      enabled: true
+      enabled: false
     ```
 
 1. Save the file and [restart GitLab][] for the changes to take effect.