in_tail: Align the comments for timer of progress check

Signed-off-by: Hiroshi Hatake <hiroshi@chronosphere.io>

Author: cosmo0920

plugins/in_tail/tail_config.h

@@ -73,11 +73,11 @@ struct flb_tail_config {
     int coll_fd_inactive;
     int coll_fd_dmode_flush;
     int coll_fd_mult_flush;
-    int coll_fd_progress_check;
 
     /* Backend collectors */
     int coll_fd_fs1;           /* used by fs_inotify & fs_stat */
     int coll_fd_fs2;           /* only used by fs_stat         */
+    int coll_fd_progress_check; /* inotify missed-event recovery timer */
 
     /* Configuration */
     int dynamic_tag;           /* dynamic tag ? e.g: abc.*     */

plugins/in_tail/tail_fs_inotify.c

@@ -433,7 +433,10 @@ int flb_tail_fs_inotify_init(struct flb_input_instance *in,
     }
     ctx->coll_fd_fs1 = ret;
 
-    /* Register callback to check current tail offsets */
+    /*
+     * Keep the collector ID so the recovery timer follows the inotify
+     * collector through input pause and resume transitions.
+     */
     ret = flb_input_set_collector_time(in, in_tail_progress_check_callback,
                                        ctx->progress_check_interval,
                                        ctx->progress_check_interval_nsec,