Fix #1703, update docs for CFE_FS_BackgroundFileDumpRequest

Update notes to better clarify that the meta object must persist
for the duration of the dump operation, which occurs in another task,
so it must not be on the stack.

modules/core_api/fsw/inc/cfe_fs.h

@@ -291,8 +291,8 @@ CFE_Status_t CFE_FS_ExtractFilenameFromPath(const char *OriginalPath, char *File
 **        Puts the previously-initialized metadata into the pending request queue
 **
 ** \par Assumptions, External Events, and Notes:
-**        Metadata structure should be stored in a static memory area (not on heap) as it
-**        must persist and be accessible by the file writer task throughout the asynchronous
+**        Metadata structure should be stored in a persistent memory area (not on stack) as
+**        it must remain accessible by the file writer task throughout the asynchronous
 **        job operation.
 **
 ** \param[inout] Meta        The background file write persistent state object