update syntax gram for kill, prepare and show stats_healthy (#2880

)

* update syntax gram for `kill`, `prepare` and `show stats_healthy`

* Update statistics.md

Co-authored-by: Keke Yi <40977455+yikeke@users.noreply.github.com>
Co-authored-by: ti-srebot <66930949+ti-srebot@users.noreply.github.com>

sql-statements/sql-statement-kill.md

@@ -17,6 +17,10 @@ By design, this statement is not compatible with MySQL by default. This helps pr
 
 ![KillStmt](/media/sqlgram/KillStmt.png)
 
+**KillOrKillTiDB:**
+
+![KillOrKillTiDB](/media/sqlgram/KillOrKillTiDB.png)
+
 ## Examples
 
 ```sql

sql-statements/sql-statement-prepare.md

@@ -15,6 +15,10 @@ The `PREPARE` statement provides an SQL interface to server-side prepared statem
 
 ![PreparedStmt](/media/sqlgram/PreparedStmt.png)
 
+**PrepareSQL:**
+
+![PrepareSQL](/media/sqlgram/PrepareSQL.png)
+
 ## Examples
 
 ```sql

statistics.md

@@ -190,13 +190,13 @@ Currently, the `SHOW STATS_META` statement returns the following 6 columns:
 
 You can use the `SHOW STATS_HEALTHY` statement to check the health state of tables and roughly estimate the accuracy of the statistics. When `modify_count` >= `row_count`, the health state is 0; when `modify_count` < `row_count`, the health state is (1 - `modify_count`/`row_count`) * 100.
 
-The syntax is as follows. You can use `ShowLikeOrWhere` to filter the information you need:
+The synopsis of `SHOW STATS_HEALTHY` is:
 
-{{< copyable "sql" >}}
+![ShowStatsHealthy](/media/sqlgram/ShowStatsHealthy.png)
 
-```sql
-SHOW STATS_HEALTHY [ShowLikeOrWhere];
-```
+and the synopsis of the `ShowLikeOrWhereOpt` part is:
+
+![ShowLikeOrWhereOpt](/media/sqlgram/ShowLikeOrWhereOpt.png)
 
 Currently, the `SHOW STATS_HEALTHY` statement returns the following 4 columns:
 
@@ -312,4 +312,4 @@ Syntax:
 LOAD STATS 'file_name'
 ```
 
-`file_name` is the file name of the statistics to be imported.
+`file_name` is the file name of the statistics to be imported.