message: Explain that unused mempool memory is added to -dbcache
diff: @@ -352,7 +352,7 @@ void SetupServerArgs()
  gArgs.AddArg("-conf=<file>", strprintf("Specify configuration file. Relative paths will be prefixed by datadir location. (default: %s)", BITCOIN_CONF_FILENAME), false, OptionsCategory::OPTIONS);
  gArgs.AddArg("-datadir=<dir>", "Specify data directory", false, OptionsCategory::OPTIONS);
  gArgs.AddArg("-dbbatchsize", strprintf("Maximum database write batch size in bytes (default: %u)", nDefaultDbBatchSize), true, OptionsCategory::OPTIONS);
  - gArgs.AddArg("-dbcache=<n>", strprintf("Set database cache size in MiB (%d to %d, default: %d)", nMinDbCache, nMaxDbCache, nDefaultDbCache), false, OptionsCategory::OPTIONS);
  + gArgs.AddArg("-dbcache=<n>", strprintf("Maximum database cache size <n> MiB (%d to %d, default: %d). In addition, unused mempool memory is shared for this cache (see -maxmempool).", nMinDbCache, nMaxDbCache, nDefaultDbCache), false, OptionsCategory::OPTIONS);
  gArgs.AddArg("-debuglogfile=<file>", strprintf("Specify location of debug log file. Relative paths will be prefixed by a net-specific datadir location. (-nodebuglogfile to disable; default: %s)", DEFAULT_DEBUGLOGFILE), false, OptionsCategory::OPTIONS);
  gArgs.AddArg("-feefilter", strprintf("Tell other nodes to filter invs to us by our mempool min fee (default: %u)", DEFAULT_FEEFILTER), true, OptionsCategory::OPTIONS);
  gArgs.AddArg("-includeconf=<file>", "Specify additional configuration file, relative to the -datadir path (only useable from configuration file, not command line)", false, OptionsCategory::OPTIONS);
  