doc: add example for show table distributed

docs/en/12-taos-sql/24-show.md

@@ -178,6 +178,77 @@ SHOW TABLE DISTRIBUTED table_name;
 
 Shows how table data is distributed.
 
+Examples： show table distributed d0\G;   Display the block distribution of table `d0` in detailed format.
+
+*************************** 1.row ***************************
+_block_dist: Total_Blocks=[5] Total_Size=[93.65 Kb] Average_size=[18.73 Kb] Compression_Ratio=[23.98 %]
+
+Total_Blocks :  Table `d0` contains total 5 blocks
+Total_Size:  The total size of all the data blocks in table `d0` is 93.65 KB 
+Average_size:  The average size of each block is 18.73 KB
+Compression_Ratio: The data compression rate is 23.98%
+ 
+*************************** 2.row ***************************
+_block_dist: Total_Rows=[20000] Inmem_Rows=[0] MinRows=[3616] MaxRows=[4096] Average_Rows=[4000]
+
+Total_Rows: Table `d0` contains 20,000 rows
+Inmem_Rows： The rows still in memory, i.e. not committed in disk, is 0, i.e. none such rows
+MinRows：  The minimum number of rows in a block is 3,616 
+MaxRows： The maximum number of rows in a block is 4,096B
+Average_Rows： The average number of rows in a block is 4,000
+
+*************************** 3.row ***************************
+_block_dist: Total_Tables=[1] Total_Files=[2]
+
+Total_Tables:  The number of child tables, 1 in this example
+Total_Files：   The number of files storing the table's data, 2 in this example
+
+*************************** 4.row ***************************
+_block_dist: --------------------------------------------------------------------------------
+*************************** 5.row ***************************
+_block_dist: 0100 |
+*************************** 6.row ***************************
+_block_dist: 0299 |
+*************************** 7.row ***************************
+_block_dist: 0498 |
+*************************** 8.row ***************************
+_block_dist: 0697 |
+*************************** 9.row ***************************
+_block_dist: 0896 |
+*************************** 10.row ***************************
+_block_dist: 1095 |
+*************************** 11.row ***************************
+_block_dist: 1294 |
+*************************** 12.row ***************************
+_block_dist: 1493 |
+*************************** 13.row ***************************
+_block_dist: 1692 |
+*************************** 14.row ***************************
+_block_dist: 1891 |
+*************************** 15.row ***************************
+_block_dist: 2090 |
+*************************** 16.row ***************************
+_block_dist: 2289 |
+*************************** 17.row ***************************
+_block_dist: 2488 |
+*************************** 18.row ***************************
+_block_dist: 2687 |
+*************************** 19.row ***************************
+_block_dist: 2886 |
+*************************** 20.row ***************************
+_block_dist: 3085 |
+*************************** 21.row ***************************
+_block_dist: 3284 |
+*************************** 22.row ***************************
+_block_dist: 3483 |||||||||||||||||  1 (20.00%)
+*************************** 23.row ***************************
+_block_dist: 3682 |
+*************************** 24.row ***************************
+_block_dist: 3881 |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||  4 (80.00%)
+Query OK, 24 row(s) in set (0.002444s)
+
+  The above show the block distribution percentage according to the number of rows in each block. In the above example, `_block_dist: 3483 |||||||||||||||||  1 (20.00%)` means there is one block whose rows is between 3,483 and 3,681. `_block_dist: 3881 |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||  4 (80.00%)` means there are 4 blocks whose rows is between 3,881 and 4,096. The number of blocks whose rows fall in other range is zero.
+
 ## SHOW TAGS
 
 ```sql