docs(godot): Use SentryUnit constants in metrics examples (#16794)

Co-authored-by: Claude <[email protected]>
Co-authored-by: JoshuaMoelans <[email protected]>
Co-authored-by: Alex Krawiec <[email protected]>

Author: 4 people

platform-includes/metrics/usage/godot.mdx

@@ -28,15 +28,15 @@ Track current values at a point in time, like a snapshot. Sentry computes aggreg
 SentrySDK.metrics.gauge("players_online", lobby.get_player_count())
 
 # With a unit
-SentrySDK.metrics.gauge("memory_usage", OS.get_static_memory_usage(), "byte")
+SentrySDK.metrics.gauge("memory_usage", OS.get_static_memory_usage(), SentryUnit.byte)
 ```
 
 ### Distributions
 
 Record numeric values to compute statistical aggregates such as p50, p95, avg, min, and max:
 
 ```GDScript
-SentrySDK.metrics.distribution("level_load_time", load_time, "millisecond")
+SentrySDK.metrics.distribution("level_load_time", load_time, SentryUnit.millisecond)
 ```
 
 ### Custom Attributes
@@ -46,7 +46,7 @@ Add attributes to filter and group metrics in Sentry:
 ```GDScript
 SentrySDK.metrics.count("enemies_spawned", wave_size, {"level": "castle"})
 
-SentrySDK.metrics.distribution("level_load_time", load_time, "millisecond", {
+SentrySDK.metrics.distribution("level_load_time", load_time, SentryUnit.millisecond, {
 	"scene": get_tree().current_scene.name
 })
 ```
@@ -55,15 +55,15 @@ Attributes support `bool`, `int`, `float`, and `String` data types. Other types
 
 ### Units
 
-For gauge and distribution metrics, you can specify a unit as a string to help Sentry display values in a human-readable format. See [supported units](https://develop.sentry.dev/sdk/foundations/data-model/attributes/#units) for the full list.
+For gauge and distribution metrics, you can specify a unit to help Sentry display values in a human-readable format. The `SentryUnit` singleton provides predefined constants for common units. See [supported units](https://develop.sentry.dev/sdk/foundations/data-model/attributes/#units) for the full list.
 
 ```GDScript
 # Duration units
-SentrySDK.metrics.distribution("level_load_time", load_time, "millisecond")
+SentrySDK.metrics.distribution("level_load_time", load_time, SentryUnit.millisecond)
 
 # Information units
-SentrySDK.metrics.gauge("memory_usage", OS.get_static_memory_usage(), "byte")
+SentrySDK.metrics.gauge("memory_usage", OS.get_static_memory_usage(), SentryUnit.byte)
 
-# Custom units
-SentrySDK.metrics.distribution("frame_rate", Engine.get_frames_per_second(), "fps")
+# Custom units (as strings)
+SentrySDK.metrics.gauge("items_in_inventory", item_count, "item")
 ```