Update README with version details and cleanup info

Reorganized version information and added data cleanup instructions.

Author: githubflyideas

README.md

@@ -7,11 +7,6 @@
 A smokeping-like network tool.One binary file.   
 Just scp and run.   
 
-
-*v2.10.2:Storage is JSON;   history is kept for 300 days by default  
-*v3.03  :Storage is SQLite; history is kept for 40  days by default (--days=300 for longer)
-
-
 ```bash
 mkdir /home/pingping -p &&cd /home/pingping
 
@@ -33,6 +28,8 @@ Add target host
  echo "1.2.3.4 myhost pace=fast"    >> targets/ping.list
  echo "10.0.0.5:443 ads-api"        >> targets/tcp.list
 ```
+*v2.10.2:Storage is JSON;   history is kept for 300 days by default  
+*v3.03  :Storage is SQLite; history is kept for 40  days by default (--days=300 for longer)   
 Data cleanup
 Retention is fixed at 300 days. To purge earlier by hand, the bundled `clean.sh` is all you need
 (data is plain per-day JSONL, so cleanup is just find+delete):