message: doc: fix undo data filename (s/undo???.dat/rev???.dat/)
diff: @@ -400,7 +400,7 @@ private:
  void FindFilesToPruneManual(std::set<int>& setFilesToPrune, int nManualPruneHeight, int chain_tip_height);
  /**
  - * Prune block and undo files (blk???.dat and undo???.dat) so that the disk space used is less than a user-defined target.
  + * Prune block and undo files (blk???.dat and rev???.dat) so that the disk space used is less than a user-defined target.
  * The user sets the target (in MB) on the command line or in config file. This will be run on startup and whenever new
  * space is allocated in a block or undo file, staying below the target. Changing back to unpruned requires a reindex
  * (which in this case means the blockchain must be re-downloaded.)
  