build.sh: fix json files cleanup

Signed-off-by: Damien Grisonnet <dgrisonn@redhat.com>

README.md

@@ -243,8 +243,12 @@ PATH="$(pwd)/tmp/bin:${PATH}"
 rm -rf manifests
 mkdir -p manifests/setup
 
-                                               # optional, but we would like to generate yaml, not json
-jsonnet -J vendor -m manifests "${1-example.jsonnet}" | xargs -I{} sh -c 'cat {} | gojsontoyaml > {}.yaml; rm -f {}' -- {}
+# Calling gojsontoyaml is optional, but we would like to generate yaml, not json
+jsonnet -J vendor -m manifests "${1-example.jsonnet}" | xargs -I{} sh -c 'cat {} | gojsontoyaml > {}.yaml' -- {}
+
+# Make sure to remove json files
+find manifests -type f ! -name '*.yaml' -delete
+rm kustomization
 
 ```