message: docs: Move FindFilesToPrune{,Manual} doxygen comment
  [META] This is a pure comment commit.
  They belong in the member declarations in the header file.
diff: @@ -331,8 +331,24 @@ class BlockManager
  friend CChainState;
  private:
  - // See definition for documentation
  + /* Calculate the block/rev files to delete based on height specified by user with RPC command pruneblockchain */
  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.
  + * 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.)
  + *
  + * Pruning functions are called from FlushStateToDisk when the global fCheckForPruning flag has been set.
  + * Block and undo files are deleted in lock-step (when blk00003.dat is deleted, so is rev00003.dat.)
  + * Pruning cannot take place until the longest chain is at least a certain length (100000 on mainnet, 1000 on testnet, 1000 on regtest).
  + * Pruning will never delete a block within a defined distance (currently 288) from the active chain's tip.
  + * The block index is updated by unsetting HAVE_DATA and HAVE_UNDO for any blocks that were stored in the deleted files.
  + * A db flag records the fact that at least some block files have been pruned.
  + *
  + * @param[out] setFilesToPrune The set of file indices that can be unlinked will be returned
  + */
  void FindFilesToPrune(std::set<int>& setFilesToPrune, uint64_t nPruneAfterHeight, int chain_tip_height, bool is_ibd);
  public:
  