revise readme

inputs

   "{{ project_name }}.raw_name": "{{ raw_name }}",
   "{{ project_name }}.new_name": "{{ new_name }}",
   "{{ project_name }}.docker": "registry.cn-shanghai.aliyuncs.com/pgx-docker-registry/sentieon-genomics:v2018.08.01",
-  "{{ project_name }}.disk_size": "{{ disk_size }}"
+  "{{ project_name }}.disk_size": "{{ disk_size }}",
+  "{{ project_name }}.cluster_config": "{{ cluster if cluster != '' else 'OnDemand bcs.sn1ne.large img-ubuntu-vpc' }}"
 }

tasks/cat_rename.wdl

 	String new_name
 	String disk_size
 	String docker
+	String cluster_config
 
 	command <<<
 		cat ${raw_name}/clean/*_1.fq.gz > ${new_name}_1.fq.gz

workflow.wdl

 	String disk_size
 	File raw_name
 	String new_name
+	String cluster_config
 
 	call cat_rename.cat_rename as cat_rename {
 		input:
 			new_name=new_name,
 			docker=docker,
 			disk_size=disk_size
+			cluster_config=cluster_config
 	}
 }