Update Dart.gitignore

Dart.gitignore

@@ -4,9 +4,9 @@
 .packages
 .pub/
 build/
-# If you're building an application, you may want to check-in your pubspec.lock.
+# If you're building an application, you may want to check-in your pubspec.lock
 pubspec.lock
 
-# Directory created by dartdoc.
+# Directory created by dartdoc
 # If you don't generate documentation locally you can remove this line.
 doc/api/