Add documentation

Author: Luca Forstner

packages/types/src/globals.ts

@@ -1,3 +1,10 @@
+/*
+ * This file defines flags and constants that can be modified during compile time in order to facilitate tree shaking
+ * for users.
+ *
+ * "Magic strings" like `__SENTRY_DEBUG__` must be replaced with actual values or safe statements during our build process.
+ */
+
 declare global {
   const __DEBUG_BUILD__: boolean;
 }