Update user-guide

Issue: #3717
Signed-off-by: yongjunhong <[email protected]>

Author: YongGoose

documentation/src/docs/asciidoc/user-guide/extensions.adoc

@@ -289,6 +289,20 @@ Specifically, a custom extension can be registered by supplying its fully qualif
 name in a file named `org.junit.jupiter.api.extension.Extension` within the
 `/META-INF/services` folder in its enclosing JAR file.
 
+[[automatic-extension-registration-pattern-matching]]
+===== Pattern Matching Syntax
+
+Pattern matching syntax is used to automatically detect and register extensions. Here are some examples of pattern matching syntax:
+
+- `*`: includes all extensions.
+- `org.junit.*`: includes every extension under the `org.junit` base package and any of its subpackages.
+- `*.MyExtension`: includes every extension whose simple class name is exactly `MyExtension`.
+- `*System*`: includes every extension whose FQCN contains `System`.
+- `*System*, *Dev*`: includes every extension whose FQCN contains `System` or `Dev`.
+- `org.example.MyExtension, org.example.TheirExtension`: includes extensions whose FQCN is exactly `org.example.MyExtension` or `org.example.TheirExtension`.
+
+> **Note**: A class that matches both an inclusion and exclusion pattern will be excluded.
+
 [[extensions-registration-automatic-enabling]]
 ===== Enabling Automatic Extension Detection
 
@@ -368,7 +382,7 @@ following system property.
 [[extensions-conditions-deactivation-patterns]]
 ===== Pattern Matching Syntax
 
-Refer to <<running-tests-config-params-deactivation-pattern>> for details.
+Pattern matching syntax is used to automatically detect and register extensions. For more details, refer to the <<automatic-extension-registration-pattern-matching,Pattern Matching Syntax>> section.
 
 [[extensions-test-instance-pre-construct-callback]]
 === Test Instance Pre-construct Callback