Added keyboard shortcuts to signed out menu

app/views/layouts/nav/_explore.html.haml

 %ul
   = nav_link(path: ['dashboard#show', 'root#show', 'projects#trending', 'projects#starred', 'projects#index'], html_options: {class: 'home'}) do
-    = link_to explore_root_path, title: 'Projects' do
+    = link_to explore_root_path, title: 'Projects', class: 'dashboard-shortcuts-projects' do
+      .shortcut-mappings
+        .key
+          = icon('arrow-up', 'aria-label' => 'hidden')
+          P
       %span
         Projects
   = nav_link(controller: [:groups, 'groups/milestones', 'groups/group_members']) do
-    = link_to explore_groups_path, title: 'Groups' do
+    = link_to explore_groups_path, title: 'Groups', class: 'dashboard-shortcuts-groups' do
+      .shortcut-mappings
+        .key
+          = icon('arrow-up', 'aria-label' => 'hidden')
+          G
       %span
         Groups
   = nav_link(controller: :snippets) do
-    = link_to explore_snippets_path, title: 'Snippets' do
+    = link_to explore_snippets_path, title: 'Snippets', class: 'dashboard-shortcuts-snippets' do
+      .shortcut-mappings
+        .key
+          = icon('arrow-up', 'aria-label' => 'hidden')
+          S
       %span
         Snippets
+  %li.divider
   = nav_link(controller: :help) do
     = link_to help_path, title: 'Help' do
       %span

spec/features/dashboard/shortcuts_spec.rb

 require 'spec_helper'
 
 feature 'Dashboard shortcuts', feature: true, js: true do
-  before do
-    login_as :user
-    visit root_dashboard_path
-  end
+  context 'logged in' do
+    before do
+      login_as :user
+      visit root_dashboard_path
+    end
+
+    scenario 'Navigate to tabs' do
+      find('body').native.send_keys([:shift, 'P'])
+
+      check_page_title('Projects')
+
+      find('body').native.send_key([:shift, 'I'])
+
+      check_page_title('Issues')
 
-  scenario 'Navigate to tabs' do
-    find('body').native.send_keys([:shift, 'P'])
+      find('body').native.send_key([:shift, 'M'])
+
+      check_page_title('Merge Requests')
+
+      find('body').native.send_keys([:shift, 'T'])
+
+      check_page_title('Todos')
+    end
+  end
 
-    check_page_title('Projects')
+  context 'logged out' do
+    before do
+      visit explore_root_path
+    end
 
-    find('body').native.send_key([:shift, 'I'])
+    scenario 'Navigate to tabs' do
+      find('body').native.send_keys([:shift, 'P'])
 
-    check_page_title('Issues')
+      expect(page).to have_content('No projects found')
 
-    find('body').native.send_key([:shift, 'M'])
+      find('body').native.send_keys([:shift, 'G'])
 
-    check_page_title('Merge Requests')
+      expect(page).to have_content('No public groups')
 
-    find('body').native.send_keys([:shift, 'T'])
+      find('body').native.send_keys([:shift, 'S'])
 
-    check_page_title('Todos')
+      expect(page).to have_selector('.snippets-list-holder')
+    end
   end
 
   def check_page_title(title)