Update best-practices-least-privileged-account.md

Updated MySQL username in the right format 'username@ip'.

Author: Molishv

articles/migrate/best-practices-least-privileged-account.md

@@ -370,7 +370,7 @@ GRANT USAGE ON *.* TO 'username@ip';
 GRANT PROCESS ON *.* TO 'username@ip'; 
 GRANT SELECT (User, Host, Super_priv, File_priv, Create_tablespace_priv, Shutdown_priv) ON mysql.user TO 'username@ip';
 GRANT SELECT ON information_schema.* TO 'username@ip';
-GRANT SELECT ON performance_schema.* TO username@ip';
+GRANT SELECT ON performance_schema.* TO 'username@ip';
 
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