Add translations for flag improvements

Refs flarum/flags#18.
Closes #148.

locale/flarum-flags.yml

@@ -10,6 +10,7 @@ flarum-flags:
     # These translations are used in the Permissions page of the admin interface.
     permissions:
       flag_posts_label: Flag posts
+      flag_own_posts_label: Allow users to flag their own posts
       view_flags_label: View flagged posts
 
     # These translations are used in the Flags Settings modal dialog.
@@ -24,11 +25,13 @@ flarum-flags:
     flag_post:
       confirmation_message: Thank you for flagging this post. Our moderators will look into it.
       dismiss_button: => core.ref.okay
+      reason_details_placeholder: Additional details (optional)
       reason_inappropriate_label: Inappropriate
       reason_inappropriate_text: "This post is offensive, abusive, or violates our <a>community guidelines</a>."
+      reason_missing_message: Please provide some details for our moderators.
       reason_off_topic_label: "Off-topic"
       reason_off_topic_text: This post is not relevant to the current discussion and should be moved elsewhere.
-      reason_other_label: Other
+      reason_other_label: Other (please specify)
       reason_spam_label: Spam
       reason_spam_text: This post is an advertisement.
       submit_button: => flarum-flags.ref.flag_post