doc: Override default value for RandomNumberGenerator.seed

It's non-deterministic so it's better to show a fixed value like 0 instead of
having it potentially change whenever `randomize()` is called.

Fixes #43317.

core/math/random_number_generator.cpp

@@ -33,7 +33,6 @@
 void RandomNumberGenerator::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("set_seed", "seed"), &RandomNumberGenerator::set_seed);
 	ClassDB::bind_method(D_METHOD("get_seed"), &RandomNumberGenerator::get_seed);
-	ADD_PROPERTY(PropertyInfo(Variant::INT, "seed"), "set_seed", "get_seed");
 
 	ClassDB::bind_method(D_METHOD("randi"), &RandomNumberGenerator::randi);
 	ClassDB::bind_method(D_METHOD("randf"), &RandomNumberGenerator::randf);
@@ -41,4 +40,8 @@ void RandomNumberGenerator::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("randf_range", "from", "to"), &RandomNumberGenerator::randf_range);
 	ClassDB::bind_method(D_METHOD("randi_range", "from", "to"), &RandomNumberGenerator::randi_range);
 	ClassDB::bind_method(D_METHOD("randomize"), &RandomNumberGenerator::randomize);
+
+	ADD_PROPERTY(PropertyInfo(Variant::INT, "seed"), "set_seed", "get_seed");
+	// Default value is non-deterministic, override it for doc generation purposes.
+	ADD_PROPERTY_DEFAULT("seed", 0);
 }

doc/classes/RandomNumberGenerator.xml

@@ -74,9 +74,10 @@
 		</method>
 	</methods>
 	<members>
-		<member name="seed" type="int" setter="set_seed" getter="get_seed" default="-6398989897141750821">
+		<member name="seed" type="int" setter="set_seed" getter="get_seed" default="0">
 			The seed used by the random number generator. A given seed will give a reproducible sequence of pseudo-random numbers.
 			[b]Note:[/b] The RNG does not have an avalanche effect, and can output similar random streams given similar seeds. Consider using a hash function to improve your seed quality if they're sourced externally.
+			[b]Note:[/b] The default value of this property is pseudo-random, and changes when calling [method randomize]. The [code]0[/code] value documented here is a placeholder, and not the actual default seed.
 		</member>
 	</members>
 	<constants>