Update jsonrpc-api.md to document 'owner' property (#22074) (#22077)

* Update jsonrpc-api.md to document 'owner' property

Documents 'owner' property on the token balances struct.

* Update docs/src/developing/clients/jsonrpc-api.md

Co-authored-by: Tyera Eulberg <teulberg@gmail.com>
(cherry picked from commit 67c8034)

Co-authored-by: splintred <91386295+splintred@users.noreply.github.com>

docs/src/developing/clients/jsonrpc-api.md

@@ -589,6 +589,7 @@ The JSON structure of token balances is defined as a list of objects in the foll
 
 - `accountIndex: <number>` - Index of the account in which the token balance is provided for.
 - `mint: <string>` - Pubkey of the token's mint.
+- `owner: <string>` - Pubkey of token balance's owner.
 - `uiTokenAmount: <object>` -
   - `amount: <string>` - Raw amount of tokens as a string, ignoring decimals.
   - `decimals: <number>` - Number of decimals configured for token's mint.