Fix language export variables (#1689)

* Fix naming of JS locale constants

* Improve the translation instructions re: const names

app/assets/javascripts/components/locales/bg.jsx

@@ -65,4 +65,4 @@ const bg = {
   "notifications.column_settings.reblog": "Споделяния:",
 };
 
-export default en;
+export default bg;

app/assets/javascripts/components/locales/de.jsx

-const en = {
+const de = {
   "column_back_button.label": "Zurück",
   "lightbox.close": "Schließen",
   "loading_indicator.label": "Lade…",
@@ -74,4 +74,4 @@ const en = {
   "missing_indicator.label": "Nicht gefunden"
 };
 
-export default en;
+export default de;

app/assets/javascripts/components/locales/en.jsx

@@ -5,6 +5,7 @@
  *   1. to add your new string here; and
  *   2. to remove old strings that are no longer needed; and
  *   3. to sort the strings by the key.
+ #   4. To rename the `en` const name and export default name to match your locale.
  * Thanks!
  */
 const en = {