Add get_latest_version for opengl

Author: Suraj-Yadav

lib/docs/scrapers/opengl.rb

@@ -27,5 +27,9 @@ class Opengl < FileScraper
       self.release = '2.1'
       self.base_url = "https://registry.khronos.org/OpenGL-Refpages/gl#{self.version}/"
     end
+
+    def get_latest_version(opts)
+      get_latest_github_commit_date('KhronosGroup', 'OpenGL-Refpages', opts)
+    end
   end
 end