Update README.md

README.md

@@ -8,7 +8,8 @@ The demo is Cosmos SDK `0.40.0-rc3` compatible, please follow these steps in ord
 
 1. Make sure Docker is installed on your system. This is needed to start a local blockchain.
 2. Make sure `git-lfs` is [installed](https://docs.github.com/en/github/managing-large-files/versioning-large-files/installing-git-large-file-storage) on your system. This is needed to clone [cosmos/cosmjs](https://github.com/cosmos/cosmjs).
-3. Start the CosmJS development blockchain "simapp":
+3. Make sure you have access to core util commands like `realpath` if you're using Mac by [installing them](https://github.com/whatwg/html-build/issues/90) if they're missing.
+4. Start the CosmJS development blockchain "simapp":
    ```sh
    git clone https://github.com/cosmos/cosmjs.git
    cd cosmjs