Add changes into change-log

docs/release-notes/change-log.md

@@ -11,6 +11,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 
 ## Unreleased
 
+* Add `substreams codegen subgraph` command that takes a substreams `module` and an `spkg` and that generates a simple `subgraph` from the `module` output.  
 * On `substreams init` command, if flag `--state-file` is provided, the state file is used by default for project generation.
 * In `substreams init` command, the state file is named using a `Date format` and not using `Unix` anymore.
 * Added an execution timeout of 3 minutes per block by default (can be overriden in tier1/tier2 Configs) -- this is useful when an external (eth_call) is stuck on a forked block hash.