Add note about default-auth for MySQL 8.0 clients (pingcap#2669) (pingcap#2741)

Signed-off-by: sre-bot <sre-bot@pingcap.com>

Author: sre-bot

connectors-and-apis.md

@@ -29,6 +29,10 @@ TiDB is compatible with all Connectors and APIs of MySQL (5.6, 5.7), including:
 
 Oracle develops the following APIs and TiDB is compatible with all of them:
 
+> **Note:**
+>
+> + To connect to TiDB using a MySQL Connector from MySQL 8.0, you must explicitly specify `default-auth=mysql_native_password`, because `mysql_native_password` is [no longer the default plugin](https://dev.mysql.com/doc/refman/8.0/en/upgrading-from-previous-series.html#upgrade-caching-sha2-password).
+
 - [MySQL Connector/C++](https://dev.mysql.com/doc/refman/5.7/en/connector-cpp-info.html)：to enable C++ applications to connect to MySQL
 - [MySQL Connector/J](https://dev.mysql.com/doc/refman/5.7/en/connector-j-info.html)：to enable Java applications to connect to MySQL using the standard JDBC API
 - [MySQL Connector/Net](https://dev.mysql.com/doc/refman/5.7/en/connector-net-info.html)：to enable .Net applications to connect to MySQL; [MySQL for Visual Studio](https://dev.mysql.com/doc/visual-studio/en/) uses this; support Microsoft Visual Studio 2012, 2013, 2015 and 2017 versions

security-compatibility-with-mysql.md

@@ -10,6 +10,7 @@ aliases: ['/docs/v2.1/reference/security/compatibility/']
 TiDB supports similar security functionality to MySQL 5.7, with the following exceptions:
 
 - Only the `mysql_native_password` authentication scheme is supported
+    - In MySQL 8.0, `mysql_native_password` is [no longer the default/preferred plugin](https://dev.mysql.com/doc/refman/8.0/en/upgrading-from-previous-series.html#upgrade-caching-sha2-password). To connect to TiDB using a MySQL client from MySQL 8.0, you must explicitly specify `default-auth=mysql_native_password`.
 - External authentication (such as with LDAP) is not currently supported
 - Column level permissions are not supported
 - Using certificates for authentication is not supported [#9708](https://github.com/pingcap/tidb/issues/9708)

tidb-specific-system-variables.md

@@ -249,7 +249,7 @@ set @@global.tidb_distsql_scan_concurrency = 10
 - Default value: 2
 - This variable is used to increase the weight of the maximum time of TiDB `backoff`, that is, the maximum retry time for sending a retry request when an internal network or other component (TiKV, PD) failure is encountered. This variable can be used to adjust the maximum retry time and the minimum value is 1.
 
-    For example, the base timeout for TiDB to take TSO from PD is 15 seconds. When `tidb_backoff_weight = 2`, the maximum timeout for taking TSO is: *base time * 2 = 30 seconds*.
+    For example, the base timeout for TiDB to take TSO from PD is 15 seconds. When `tidb_backoff_weight = 2`, the maximum timeout for taking TSO is: *base time \* 2 = 30 seconds*.
 
     In the case of a poor network environment, appropriately increasing the value of this variable can effectively alleviate error reporting to the application end caused by timeout. If the application end wants to receive the error information more quickly, minimize the value of this variable.
 

user-account-management.md

@@ -25,6 +25,10 @@ Or use the abbreviation of command line parameters:
 shell> mysql -P 4000 -u xxx -p
 ```
 
+> **Note:**
+>
+> + To connect to TiDB using a MySQL client from MySQL 8.0, you must explicitly specify `--default-auth=mysql_native_password`, because `mysql_native_password` is [no longer the default plugin](https://dev.mysql.com/doc/refman/8.0/en/upgrading-from-previous-series.html#upgrade-caching-sha2-password).
+
 ## Add user accounts
 
 You can create TiDB accounts in two ways: