typo fix

packages/js/src/jsonrpc.ts

@@ -190,7 +190,7 @@ export class JsonRpcProvider extends JSONRpc {
    * to wait a fraction of the time it takes to produce the same number of blocks.
    *
    * Estimate as to how long it takes: if our delta_height crosses `X` epochs, then it would
-   * roughly take `X * 5` seconds for the fast forward request to be processed.
+   * roughly take `X * 5` milliseconds for the fast forward request to be processed.
    *
    * Note: This is not to be confused with speeding up the current in-flight transactions;
    * the state being forwarded in this case refers to time-related state (the block height, timestamp and epoch).