chore: update transient storage sample

[zixiang2018]

Context

• fetched document should have not have "document" as a key. This additional field resulted in the toolkit not being able to decrypt and show the original document on the left text box
• Issue was was due to calling POST in transient storage API instead of getting queue number and then calling PUT document.

{
"document": { // to remove this 
  "cipherText": "",
  "iv": "",
  "tag": "",
  "type": "",
  "ttl": "",
   },  
"key": ""
}

What this PR does

• update transient storage document as the previous one was showing the wrong JSON structure (correct structure below)

{
  "cipherText": "",
  "iv": "",
  "tag": "",
  "type": "",
  "ttl": "",
  "key": ""
}