Add common span attributes

Author: cleptric

develop-docs/sdk/telemetry/spans/span-protocol.mdx

@@ -167,11 +167,22 @@ Attributes are stored as key-value pairs where each value is an object with type
 
 #### Common Attribute Keys
 
+All attributes mentioned below must be attached to every span being emitted from the SDK, depending on the platform.
+Empty attributes must be emitted.
+
 | Attribute Key | Type | Description |
 |---------------|------|-------------|
 | `sentry.release` | string | The release version of the application |
 | `sentry.environment` | string | The environment name (e.g., "production", "staging", "development") |
-| `sentry.platform` | string | The platform/language (e.g., "php", "javascript", "python") |
+| `sentry.segment.name` | string | The segment name (e.g., "GET /users") |
+| `os.name` | string | The operating system name (e.g., "Linux", "Windows", "macOS") |
+| `browser.name` | string | The browser name (e.g., "Chrome", "Firefox", "Safari") |
+| `user.id` | string | The user ID (gated by `sendDefaultPii`) |
+| `user.email` | string | The user email (gated by `sendDefaultPii`) |
+| `user.ip_address` | string | The user IP address (gated by `sendDefaultPii`) |
+| `user.username` | string | The user username (gated by `sendDefaultPii`) |
+| `thread.id` | string | The thread ID |
+| `thread.name` | string | The thread name |
 | `sentry.sdk.name` | string | Name of the Sentry SDK (e.g., "sentry.php", "sentry.javascript") |
 | `sentry.sdk.version` | string | Version of the Sentry SDK |