Add new translations

- Add new translations on SignatureSheet show page.
  Changes:
   -> "document number" to "sigantures"
   -> "documents" to "users"

- Remove unused translations from the others yml

spec/features/admin/signature_sheets_spec.rb

@@ -156,7 +156,7 @@ describe "Signature sheets" do
     expect(page).to have_content signature_sheet.created_at.strftime("%B %d, %Y %H:%M")
     expect(page).to have_content user.name
 
-    within("#document_count") do
+    within("#signature_count") do
       expect(page).to have_content 3
     end