Add missing translations (#12996)

This commit adds missing translations for #12966 and #12954.

app/javascript/mastodon/locales/defaultMessages.json

@@ -293,6 +293,10 @@
   },
   {
     "descriptors": [
+      {
+        "defaultMessage": "today",
+        "id": "relative_time.today"
+      },
       {
         "defaultMessage": "now",
         "id": "relative_time.just_now"
@@ -1742,6 +1746,14 @@
         "defaultMessage": "Home",
         "id": "column.home"
       },
+      {
+        "defaultMessage": "Show announcements",
+        "id": "home.show_announcements"
+      },
+      {
+        "defaultMessage": "Hide announcements",
+        "id": "home.hide_announcements"
+      },
       {
         "defaultMessage": "Your home timeline is empty! Visit {public} or use search to get started and meet other users.",
         "id": "empty_column.home"