improve wording

Author: guimachiavelli

reference/api/tasks.mdx

@@ -254,7 +254,7 @@ curl \
 ### `customMetadata`
 
 **Type**: String<br />
-**Description**: An arbitrary string optionally configured for `/document`-related tasks. Commonly used to keep track of which documents were processed in a specific task. 
+**Description**: An arbitrary string optionally configured for tasks adding, updating, and deleting documents. Commonly used to keep track of which documents were processed in a specific task.
 
 ### Summarized task object