Added comments for skipped tests

cms/djangoapps/contentstore/features/advanced-settings.feature

@@ -11,6 +11,7 @@ Feature: Advanced (manual) course policy
     Given I am on the Advanced Course Settings page in Studio
     Then the settings are alphabetized
 
+  # Skipped because Ubuntu ChromeDriver cannot click notification "Cancel"
   @skip
   Scenario: Test cancel editing key value
     Given I am on the Advanced Course Settings page in Studio
@@ -20,6 +21,7 @@ Feature: Advanced (manual) course policy
     And I reload the page
     Then the policy key value is unchanged
 
+  # Skipped because Ubuntu ChromeDriver cannot click notification "Save"
   @skip
   Scenario: Test editing key value
     Given I am on the Advanced Course Settings page in Studio
@@ -28,6 +30,7 @@ Feature: Advanced (manual) course policy
     And I reload the page
     Then the policy key value is changed
 
+  # Skipped because Ubuntu ChromeDriver cannot edit CodeMirror input
   @skip
   Scenario: Test how multi-line input appears
     Given I am on the Advanced Course Settings page in Studio
@@ -36,6 +39,7 @@ Feature: Advanced (manual) course policy
     And I reload the page
     Then it is displayed as formatted
 
+  # Skipped because Ubuntu ChromeDriver cannot edit CodeMirror input
   @skip
   Scenario: Test automatic quoting of non-JSON values
     Given I am on the Advanced Course Settings page in Studio

cms/djangoapps/contentstore/features/section.feature

@@ -26,6 +26,7 @@ Feature: Create Section
     And I save a new section release date
     Then the section release date is updated
 
+  # Skipped because Ubuntu ChromeDriver hangs on alert
   @skip
   Scenario: Delete section
     Given I have opened a new course in Studio

cms/djangoapps/contentstore/features/studio-overview-togglesection.feature

@@ -21,6 +21,7 @@ Feature: Overview Toggle Section
     Then I see the "Collapse All Sections" link
     And all sections are expanded
 
+    # Skipped because Ubuntu ChromeDriver hangs on alert
     @skip
 	Scenario: Collapse link is not removed after last section of a course is deleted
 		Given I have a course with 1 section

cms/djangoapps/contentstore/features/subsection.feature

@@ -32,6 +32,7 @@ Feature: Create Subsection
     And I reload the page
     Then I see the correct dates
 
+  # Skipped because Ubuntu ChromeDriver hangs on alert
   @skip
   Scenario: Delete a subsection
     Given I have opened a new course section in Studio