Updated curl code snippet to upload a attachment

docs/sending/attachments.mdx

@@ -32,11 +32,10 @@ Unvollständige Einreichungen, die durch das sendende System (Onlinedienst) nich
   $ export SUBMISSION_ID=63f0c991-0635-4e18-8a4b-fb0c01de9f5c
   $ export ATTACHMENT_ID=90ae8309-2102-4e81-a325-ceda480d0e9d
   $ export ENC_FILE_CONTENT=6r4H2H_WIzCv8Pd-uetmcbK...iVBKF3ylHRUahmZ
-  $ curl \
-      -H "Authorization: Bearer $JWT_TOKEN" \
-      -H "Content-Type: application/jose" \
-      --data "$ENC_FILE_CONTENT" \
-      -X PUT "$SUBMISSION_API/v1/submissions/$SUBMISSION_ID/attachments/$ATTACHMENT_ID"
+  $ curl -L -X PUT "$SUBMISSION_API/v1/submissions/$SUBMISSION_ID/attachments/$ATTACHMENT_ID" \
+-H "Authorization: Bearer $JWT_TOKEN" \
+-H "Content-Type: application/jose" \
+--data-raw "$ENC_FILE_CONTENT"
   ```
 
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