upadte data info

examples/callcenter/README.md

+# Callcenter 8k sample rate
+
+Data distribution:
+
+```
+676048 utts
+491.4004722221223 h
+4357792.0 text
+2.4633630739178654 text/sec
+2.6167397877068495 sec/utt
+```
+
+train/dev/test partition:
+
+```
+    33802 manifest.dev
+    67606 manifest.test
+   574640 manifest.train
+   676048 total
+```