message: add instruction on how to get log size for SPU pod
diff: @@ -39,3 +39,10 @@ IME_WAIT is normal. It's a state after a socket has closed, used by the kernel t
  ```
  +# SPU debugging
  +
  +To show log size:
  +```
  +kubectl exec fluvio-spg-main-0 -- ls -lh /var/lib/fluvio/data/spu-logs-0/<topic-name>-0/00000000000000000000.log
  +```
  +
  