Set outputDir default value in config (#5543)

Signed-off-by: Ben Sherman <[email protected]>

modules/nextflow/src/main/groovy/nextflow/config/ConfigBuilder.groovy

@@ -338,6 +338,7 @@ class ConfigBuilder {
         binding.put('baseDir', base)
         binding.put('projectDir', base)
         binding.put('launchDir', Paths.get('.').toRealPath())
+        binding.put('outputDir', Paths.get('results').toRealPath())
         binding.put('secrets', SecretsLoader.secretContext())
         return binding
     }