docs: clarify breadcrumbs behavior in README and index.ts

Author: Dobrunia

README.md

@@ -207,7 +207,7 @@ HawkCatcher.init({
 
 #### Manual breadcrumbs
 
-Add custom breadcrumbs manually (they are attached to the next event sent):
+Add custom breadcrumbs manually. Breadcrumbs accumulate in a buffer and are attached to every event until explicitly cleared via `HawkCatcher.breadcrumbs.clear()`:
 
 ```js
 HawkCatcher.breadcrumbs.add({

src/index.ts

@@ -367,7 +367,7 @@ export default class HawkCatcher {
  * Breadcrumbs API - same surface as in @hawk.so/javascript (add, get, clear)
  */
 export interface BreadcrumbsAPI {
-  /** Add a breadcrumb to the buffer (attached to the next sent event) */
+  /** Add a breadcrumb to the buffer (attached to every event until cleared) */
   add(breadcrumb: BreadcrumbInput, hint?: BreadcrumbHint): void;
 
   /** Get current breadcrumbs snapshot (oldest to newest) */