More changes suggested by Robert

doc/install/installation.md

@@ -334,7 +334,6 @@ sudo usermod -aG redis git
     # Enable packfile bitmaps
     sudo -u git -H git config --global repack.writeBitmaps true
 
-
     # Configure Redis connection settings
     sudo -u git -H cp config/resque.yml.example config/resque.yml
 

doc/update/8.11-to-8.12.md

@@ -105,7 +105,6 @@ sudo -u git -H bundle exec rake db:migrate RAILS_ENV=production
 
 # Clean up assets and cache
 sudo -u git -H bundle exec rake assets:clean assets:precompile cache:clear RAILS_ENV=production
-
 ```
 
 ### 8. Update configuration files
@@ -120,8 +119,10 @@ git diff origin/8-11-stable:config/gitlab.yml.example origin/8-12-stable:config/
 
 #### Git configuration
 
+Configure Git to generate packfile bitmaps (introduced in Git 2.0) on
+the GitLab server during `git gc`.
+
 ```sh
-# Enable packfile bitmaps
 sudo -u git -H git config --global repack.writeBitmaps true
 ```