Adjust test wording

Author: shepmaster

tests/spec/features/editions_spec.rb

@@ -10,7 +10,7 @@
     editor.set(rust_2018_code)
   end
 
-  scenario "using the 2015 channel" do
+  scenario "using the 2015 edition" do
     in_advanced_options_menu { choose '2015' }
     click_on("Run")
 
@@ -20,7 +20,7 @@
     end
   end
 
-  scenario "using the 2018 channel" do
+  scenario "using the 2018 edition" do
     in_advanced_options_menu { choose '2018' }
     click_on("Run")