rename locale filter function and improve docs

config.rb

@@ -47,7 +47,7 @@ require 'ruby-cheerio'
 helpers do
   def get_invitation_only_courses
     courses = data.courses.clone
-    courses['results'] = data.courses['results'].select { |course| not course['hidden'] and course['invitation_only'] == true and filter_course_language(course['number'], locale) }
+    courses['results'] = data.courses['results'].select { |course| not course['hidden'] and course['invitation_only'] == true and course_number_matches_locale(course['number'], locale) }
     courses
   end
 
@@ -55,7 +55,7 @@ helpers do
   # You can change this under Settings -> Advanced Settings in Studio.
   def get_enrollable_courses
     courses = data.courses.clone
-    courses['results'] = data.courses['results'].select { |course| course['invitation_only'] == false and filter_course_language(course['number'], locale)}
+    courses['results'] = data.courses['results'].select { |course| course['invitation_only'] == false and course_number_matches_locale(course['number'], locale)}
     courses
   end
 
@@ -129,8 +129,9 @@ helpers do
 
   # Our convention is to end course numbers with their language code in upper
   # case, an example course number: "TP_DR_FA" for Totem Project Desk Research
-  # Farsi
-  def filter_course_language(course_number, loc)
+  # Farsi.
+  # Returns true if the course number matches the locale.
+  def course_number_matches_locale(course_number, loc)
     loc = loc.to_s.upcase
     course_number.end_with? "_#{loc}"
   end