README.md: fix minor wording issues

Author: thomas-roos

meta-aws-demos/recipes-core/images/aws-iot-greengrass-lite-demo-image/README.md

@@ -21,10 +21,10 @@ https://github.com/aws-greengrass/aws-greengrass-lite
 
 ## BUILDING
 
+Init build environment
+
 ```bash
 . init-build-env
-bitbake $IMAGE
-runqemu slirp nographic
 ```
 
 Configure this image
@@ -233,4 +233,4 @@ Manifests:
     Artifacts:
       - URI: 's3://2024-11-27-us-east-1ab-update/update.raucb'
         Unarchive: 'NONE'
-```
+```