cherry pick pingcap#5349 to release-4.0

Signed-off-by: ti-srebot <ti-srebot@pingcap.com>

explain-overview.md

@@ -6,6 +6,10 @@ aliases: ['/docs/stable/query-execution-plan/','/docs/v4.0/query-execution-plan/
 
 # `EXPLAIN` Overview
 
+> **Note:**
+>
+> When you use the MySQL client to connect to TiDB, to read the output result in a clearer way without line wrapping, you can use the `pager less -S` command. Then, after the `EXPLAIN` result is output, you can press the right arrow <kbd>→</kbd> button on your keyboard to horizontally scroll through the output.
+
 SQL is a declarative language. It describes what the results of a query should look like, **not the methodology** to actually retrieve those results. TiDB considers all the possible ways in which a query could be executed, including using what order to join tables and whether any potential indexes can be used. The process of _considering query execution plans_ is known as SQL optimization.
 
 The `EXPLAIN` statement shows the selected execution plan for a given statement. That is, after considering hundreds or thousands of ways in which the query could be executed, TiDB believes that this _plan_ will consume the least resources and execute in the shortest amount of time:
@@ -100,4 +104,4 @@ The `operator info` can show useful information such as which conditions were ab
 * `keep order:false` shows that the semantics of this query did not require TiKV to return the results in order. If the query were to be modified to require an order (such as `SELECT * FROM t WHERE a = 1 ORDER BY id`), then this condition would be `keep order:true`.
 * `stats:pseudo` shows that the estimates shown in `estRows` might not be accurate. TiDB periodically updates statistics as part of a background operation. A manual update can also be performed by running `ANALYZE TABLE t`.
 
-Different operators output different information after the `EXPLAIN` statement is executed. You can use optimizer hints to control the behavior of the optimizer, and thereby controlling the selection of the physical operators. For example, `/*+ HASH_JOIN(t1, t2) */` means that the optimizer uses the `Hash Join` algorithm. For more details, see [Optimizer Hints](/optimizer-hints.md).
+Different operators output different information after the `EXPLAIN` statement is executed. You can use optimizer hints to control the behavior of the optimizer, and thereby controlling the selection of the physical operators. For example, `/*+ HASH_JOIN(t1, t2) */` means that the optimizer uses the `Hash Join` algorithm. For more details, see [Optimizer Hints](/optimizer-hints.md).

sql-statements/sql-statement-explain.md

@@ -28,6 +28,10 @@ TiDB supports the `EXPLAIN [options] FOR CONNECTION connection_id` statement. Ho
 
 ## `EXPLAIN` output format
 
+> **Note:**
+>
+> If you use the `mysql` client to connect to TiDB you may want to use `pager less -S` to avoid line wrapping in your terminal and instead press the right arrow on your keyboard to horizontally scroll through the explain output.
+
 Currently, `EXPLAIN` in TiDB outputs 5 columns: `id`, `estRows`, `task`, `access object`, `operator info`. Each operator in the execution plan is described by these attributes, with each row in the `EXPLAIN` output describing an operator. The description of each attribute is as follows:
 
 | Attribute name          | Description |