Remove feature gates for Repository Languages

The repository languages feature got introduced through:
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/19480. This MR
included feature flags to guard against performance regressions, which
allowed GitLab to test it on gitlab.com before the customers would be
exposed.

.com worked out fine, as shown by our internal monitoring tools, which
prompts feature gate removal.

Given the docs weren't present yet, these were added too.

5 files changed, 11 insertions, 8 deletions

diff --git a/app/views/projects/show.html.haml b/app/views/projects/show.html.haml
index 8a5abb64515..df8a5742450 100644
--- a/app/views/projects/show.html.haml
+++ b/app/views/projects/show.html.haml
@@ -21,8 +21,7 @@
   %nav.project-stats{ class: [container_class, ("limit-container-width" unless fluid_layout)] }
     = render 'stat_anchor_list', anchors: @project.statistics_anchors(show_auto_devops_callout: show_auto_devops_callout)
     = render 'stat_anchor_list', anchors: @project.statistics_buttons(show_auto_devops_callout: show_auto_devops_callout)
-    - if Feature.enabled?(:repository_languages, @project.namespace.becomes(Namespace))
-      = repository_languages_bar(@project.repository_languages)
+    = repository_languages_bar(@project.repository_languages)
 
 %div{ class: [container_class, ("limit-container-width" unless fluid_layout)] }
   - if @project.archived?
diff --git a/app/workers/detect_repository_languages_worker.rb b/app/workers/detect_repository_languages_worker.rb
index 537b8fd5963..081c0d42c27 100644
--- a/app/workers/detect_repository_languages_worker.rb
+++ b/app/workers/detect_repository_languages_worker.rb
@@ -14,8 +14,6 @@ class DetectRepositoryLanguagesWorker
     user = User.find_by(id: user_id)
     return unless project && user
 
-    return if Feature.disabled?(:repository_languages, project.namespace)
-
     try_obtain_lease do
       ::Projects::DetectRepositoryLanguagesService.new(project, user).execute
     end
diff --git a/doc/user/project/repository/img/repository_languages.png b/doc/user/project/repository/img/repository_languages.png
new file mode 100644
index 00000000000..d9fb1278e06
--- /dev/null
+++ b/doc/user/project/repository/img/repository_languages.png
diff --git a/doc/user/project/repository/index.md b/doc/user/project/repository/index.md
index 704c1777e62..1c3915a5fdd 100644
--- a/doc/user/project/repository/index.md
+++ b/doc/user/project/repository/index.md
@@ -155,6 +155,16 @@ The repository graph displays visually the Git flow strategy used in that reposi
 
 Find it under your project's **Repository > Graph**.
 
+## Repository Languages
+
+For the default branch of each repository, GitLab will determine what programming languages
+were used and display this on the projects pages.
+
+![Repository Languages bar](img/repository_languages.png)
+
+Not all files are detected, among others; documentation, 
+vendored code, and most markup languages are excluded.
+
 ## Compare
 
 Select branches to compare and view the changes inline:
diff --git a/spec/services/projects/detect_repository_languages_service_spec.rb b/spec/services/projects/detect_repository_languages_service_spec.rb
index f90d558938f..deea1189cdf 100644
--- a/spec/services/projects/detect_repository_languages_service_spec.rb
+++ b/spec/services/projects/detect_repository_languages_service_spec.rb
@@ -5,10 +5,6 @@ describe Projects::DetectRepositoryLanguagesService, :clean_gitlab_redis_shared_
 
   subject { described_class.new(project, project.owner) }
 
-  before do
-    allow(Feature).to receive(:disabled?).and_return(false)
-  end
-
   describe '#execute' do
     context 'without previous detection' do
       it 'inserts new programming languages in the database' do