docs: note about pattern in copy. (#12951)

* docs: note about pattern in copy.

* Update dml-copy-into-table.md

---------

Co-authored-by: BohuTANG <overred.shuttler@gmail.com>

Author: youngsofun

docs/doc/14-sql-commands/10-dml/dml-copy-into-table.md

@@ -184,10 +184,14 @@ externalLocation ::=
 
 Specify a list of one or more files names (separated by commas) to be loaded.
 
-### PATTERN = 'regex_pattern'
+### PATTERN = '<regex_pattern>'
 
 A [PCRE2](https://www.pcre.org/current/doc/html/)-based regular expression pattern string, enclosed in single quotes, specifying the file names to match. Click [here](#loading-data-with-pattern-matching) to see an example. For PCRE2 syntax, see http://www.pcre.org/current/doc/html/pcre2syntax.html.
 
+:::note
+Suppose there is a file `@<stage_name>/<path>/<sub_path>`, to include it, `<sub_path>` needs to match `^<regex_pattern>$`.
+:::
+
 ### FILE_FORMAT
 
 See [Input & Output File Formats](../../13-sql-reference/50-file-format-options.md).

docs/doc/15-sql-functions/112-table-functions/list_stage.md

@@ -36,10 +36,15 @@ externalStage ::= @<external_stage_name>[/<path>]
 userStage ::= @~[/<path>]
 ```
 
+### PATTERN
+
+See [COPY INTO table](/14-sql-commands/10-dml/dml-copy-into-table.md).
+
+
 ## Examples
 
 ```sql
-SELECT * FROM list_stage(location => '@my_stage/', pattern => '.log');
+SELECT * FROM list_stage(location => '@my_stage/', pattern => '.*[.]log');
 +----------------+------+------------------------------------+-------------------------------+---------+
 |      name      | size |                md5                 |         last_modified         | creator |
 +----------------+------+------------------------------------+-------------------------------+---------+