update README instructions

Author: blaix

README.md

@@ -19,8 +19,8 @@ You can point to a specific ref (commit, tag, branch) like this:
 * Update version in [`package.json`](/package.json)
 * Update package lock file: `npm install`
 * NOTE: if there was anything added or removed from the dependencies in `package-lock.json` you will need to update `flake.nix` to add them to the npm cache. TODO: automate this.
-* Update flake lock file: `nix flake update`
-* Test with `nix build .#` which should build an executable at `./result/bin/gren`
+* Update flake lock file: `nix flake update` (this may or may not update `flake.lock`)
+* Test with `nix build .#` which should build an executable you can test at `./result/bin/gren`
 * Commit the updated `package.json`, `package-lock.json` and `flake.lock` files
 * `git tag -a [version]`
 * `git push origin main --tags`