Respond to creation of a new comment.
Drupal\comment\Comment $comment: The comment object.
Note: this list is generated by pattern matching, so it may include some functions that are not actually implementations of this hook.
function hook_comment_insert(Drupal\comment\Comment $comment) {
// Reindex the node when comments are added.
search_touch_node($comment->nid->target_id);
}