Fix #151: Document PHPDoc default value rule (#430)

Author: samdark

src/internals/014-docs.md

@@ -124,6 +124,34 @@ final class MyService extends MyServiceBase
 
 PHPDoc, if present, should describe the purpose of the element it's added for.
 
+Skip default values in PHPDoc when PHP already shows them in a parameter default, promoted property default, or property
+initializer. The declaration is the source of truth, and repeating the value in text can become outdated after code
+changes.
+
+Example of incorrect code:
+
+```php
+/**
+ * @param bool $skipOnEmpty Whether to skip validation when the value is empty. Defaults to true.
+ */
+public function __construct(
+    private bool $skipOnEmpty = true,
+) {
+}
+```
+
+Example of a valid code:
+
+```php
+/**
+ * @param bool $skipOnEmpty Whether to skip validation when the value is empty.
+ */
+public function __construct(
+    private bool $skipOnEmpty = true,
+) {
+}
+```
+
 The `@see` tags must explicitly refer to class methods, properties, and constants. This is necessary
 for the correct display of links in IDEs, as well as for the correct display of links in API documentation.