add memory_usage column for show processlist doc
@@ -17,10 +17,10 @@ SHOW PROCESSLIST
```
mysql> SHOW PROCESSLIST;
-+--------------------------------------+-----------------+-------+----------+------------------+
-| id | host | state | database | extra_info |
-+--------------------------------------+-----------------+-------+----------+------------------+
-| 1e6e5ed4-5441-43da-9ed6-eb6ba9baeb64 | 127.0.0.1:60080 | Query | default | show processlist |
-| 3d283add-4f60-416d-b9ca-662120614093 | 127.0.0.1:57018 | Query | default | NULL |
-+--------------------------------------+-----------------+-------+----------+------------------+
++--------------------------------------+-----------------+-------+----------+------------------+------------------+
+| id | host | state | database | extra_info | memory_usage |
++--------------------------------------+-----------------+-------+----------+------------------+------------------+
+| 1e6e5ed4-5441-43da-9ed6-eb6ba9baeb64 | 127.0.0.1:60080 | Query | default | show processlist | 1234567891011121 |
+| 3d283add-4f60-416d-b9ca-662120614093 | 127.0.0.1:57018 | Query | default | NULL | 1234567891011121 |
++--------------------------------------+-----------------+-------+----------+------------------+------------------+
```
