doc: fix indent format explain (#16085)

* doc: fix indent format explain

* update

Author: chenkovsky

docs/source/library-user-guide/query-optimizer.md

@@ -193,7 +193,7 @@ Looking at the `EXPLAIN` output we can see that the optimizer has effectively re
 `3 as "1 + 2"`:
 
 ```text
-> explain select 1 + 2;
+> explain format indent select 1 + 2;
 +---------------+-------------------------------------------------+
 | plan_type     | plan                                            |
 +---------------+-------------------------------------------------+

docs/source/user-guide/explain-usage.md

@@ -40,7 +40,7 @@ Let's see how DataFusion runs a query that selects the top 5 watch lists for the
 site `http://domcheloveplanet.ru/`:
 
 ```sql
-EXPLAIN SELECT "WatchID" AS wid, "hits.parquet"."ClientIP" AS ip
+EXPLAIN FORMAT INDENT SELECT "WatchID" AS wid, "hits.parquet"."ClientIP" AS ip
 FROM 'hits.parquet'
 WHERE starts_with("URL", 'http://domcheloveplanet.ru/')
 ORDER BY wid ASC, ip DESC
@@ -268,7 +268,7 @@ LIMIT 10;
 We can again see the query plan by using `EXPLAIN`:
 
 ```sql
-> EXPLAIN SELECT "UserID", COUNT(*) FROM 'hits.parquet' GROUP BY "UserID" ORDER BY COUNT(*) DESC LIMIT 10;
+> EXPLAIN FORMAT INDENT SELECT "UserID", COUNT(*) FROM 'hits.parquet' GROUP BY "UserID" ORDER BY COUNT(*) DESC LIMIT 10;
 +---------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
 | plan_type     | plan                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
 +---------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

docs/source/user-guide/sql/explain.md

@@ -118,7 +118,7 @@ See [Reading Explain Plans](../explain-usage.md) for more information on how to
 0 row(s) fetched.
 Elapsed 0.004 seconds.
 
-> EXPLAIN SELECT SUM(x) FROM t GROUP BY b;
+> EXPLAIN FORMAT INDENT SELECT SUM(x) FROM t GROUP BY b;
 +---------------+-------------------------------------------------------------------------------+
 | plan_type     | plan                                                                          |
 +---------------+-------------------------------------------------------------------------------+