Add note about IPFS

README.md

@@ -4,6 +4,9 @@ This tool pins the IPFS hashes of a Kredits organisation on an IPFS node.
 
 ## Usage
 
+Make sure you have a local IPFS node running. (See `--help` for custom IPFS
+config flags, in case it is not running on localhost with default ports.)
+
 ### With NPX magic
 
     npx @67p/kredits-ipfs-pinner