Documentation tweak about dev bundle (#1252)

Author: peterbecich

CONTRIBUTING.md

@@ -47,7 +47,7 @@ spago bundle -p spago-bin
 ./bin/bundle.js bundle -p spago-bin
 
 # From now on you can use the bootstrapped build to see the changes you make:
-./bin/index.dev.js some-new-command
+./bin/index.dev.js build --pedantic-packages --some-new-build-flag
 
 # ...but you can of course still just use the global `spago` command:
 spago build