[doc] Add Auxiliary Statements for spark (#3915)

docs/content/spark/auxiliary.md

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+---
+title: "Auxiliary"
+weight: 7
+type: docs
+aliases:
+- /spark/auxiliary.html
+---
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+-->
+
+# Auxiliary Statements
+
+## Set / Reset
+The SET command sets a property, returns the value of an existing property or returns all SQLConf properties with value and meaning.
+The RESET command resets runtime configurations specific to the current session which were set via the SET command to their default values.
+To set paimon configs specifically, you need add the `spark.paimon.` prefix.
+
+```sql
+-- set spark conf
+SET spark.sql.sources.partitionOverwriteMode=dynamic;
+
+-- set paimon conf
+SET spark.paimon.file.block-size=512M;
+
+-- reset conf
+RESET spark.paimon.file.block-size;
+```
+
+## Describe table
+DESCRIBE TABLE statement returns the basic metadata information of a table. The metadata information includes column name, column type and column comment.
+
+```sql
+-- describe table
+DESCRIBE TABLE my_table;
+
+-- describe table with additional metadata
+DESCRIBE TABLE EXTENDED my_table;
+```
+
+## Show create table
+SHOW CREATE TABLE returns the CREATE TABLE statement that was used to create a given table.
+
+```sql
+SHOW CREATE TABLE my_table;
+```
+
+## Show columns
+Returns the list of columns in a table. If the table does not exist, an exception is thrown.
+
+```sql
+SHOW COLUMNS FROM my_table;
+```
+
+## Show partitions
+The SHOW PARTITIONS statement is used to list partitions of a table. An optional partition spec may be specified to return the partitions matching the supplied partition spec.
+
+```sql
+-- Lists all partitions for my_table
+SHOW PARTITIONS my_table;
+
+-- Lists partitions matching the supplied partition spec for my_table
+SHOW PARTITIONS my_table PARTITION (dt=20230817);
+```
+
+## Analyze table
+
+The ANALYZE TABLE statement collects statistics about the table, that are to be used by the query optimizer to find a better query execution plan.
+Paimon supports collecting table-level statistics and column statistics through analyze.
+
+```sql
+-- collect table-level statistics
+ANALYZE TABLE my_table COMPUTE STATISTICS;
+
+-- collect table-level statistics and column statistics for col1
+ANALYZE TABLE my_table COMPUTE STATISTICS FOR COLUMNS col1;
+
+-- collect table-level statistics and column statistics for all columns
+ANALYZE TABLE my_table COMPUTE STATISTICS FOR ALL COLUMNS;
+```