[docs] add transaction sponsorship cleos how to

docs/02_cleos/02_how-to-guides/how-to-submit-a-sponsored-transaction.md

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+## Overview
+
+This how-to guide provides instructions on how to submit, or push, a sponsored transaction using the `cleos` CLI tool.
+
+## Before you begin
+
+* Install the currently supported version of `cleos`
+
+* Understand the following:
+  * What a [transaction](https://developers.eos.io/welcome/latest/glossary/index/#transaction) is.
+  * How to generate a valid transaction JSON.
+    * Consult [cleos push transaction](https://developers.eos.io/manuals/eos/latest/cleos/command-reference/push/push-transaction) reference, and pay attention to option `-d` and `-j`.
+    * Consult [push transaction](https://developers.eos.io/manuals/eos/latest/nodeos/plugins/chain_api_plugin/api-reference/index#operation/push_transaction) endpoint for chain api plug-in, and pay attention to the payload definition.
+  * [How To Submit A Transaction](./how-to-submit-a-transaction).
+
+## Command Reference
+
+See the following reference guides for command line usage and related options for the `cleos` command:
+
+* The [cleos push transaction](https://developers.eos.io/manuals/eos/latest/cleos/command-reference/push/push-transaction) reference.
+
+## Procedure
+
+The following steps show how to:
+
+1. [Create the transaction as JSON snippet.](#1-create-the-transaction-as-json-snippet)
+2. [Send the transaction.](#2-send-the-transaction)
+
+### 1. Create the transaction as JSON snippet
+
+You can create the JSON snippet defining the transaction in two ways. In each case include the sponsorship information in the `transaction_extensions` array object. You can add only one transaction sponsorship per transaction.
+
+* Create a JSON snippet which contains a valid transaction and uses hex format for `data` field.
+
+```JSON
+{
+  "expiration": "2019-08-01T07:15:49",
+  "ref_block_num": 34881,
+  "ref_block_prefix": 2972818865,
+  "max_net_usage_words": 0,
+  "max_cpu_usage_ms": 0,
+  "delay_sec": 0,
+  "context_free_actions": [],
+  "actions": [{
+      "account": "eosio.token",
+      "name": "transfer",
+      "authorization": [{
+          "actor": "han",
+          "permission": "active"
+        }
+      ],
+      "data": "000000000000a6690000000000ea305501000000000000000453595300000000016d"
+    }
+  ],
+  "transaction_extensions": [
+      {
+        "payer": "sponsoracnt",
+        "max_net_bytes": 4096,
+        "max_cpu_us": 250,
+        "max_memory_bytes": 0
+      }
+  ],
+  "context_free_data": []
+}
+```
+
+* Alternatively, you can also create a JSON snippet that uses clear text JSON for `data` field.
+
+[[info]]
+| Be aware that if a clear text `data` field is used, `cleos` needs to fetch the smart contract's ABI using `nodeos` API. This operation has an overall performance overhead for both `cleos` and `nodeos`. On the other hand if hex data is used in the `data` field then the ABI fetching is not executed and thus the total time to send and execute the transaction is faster.
+
+```json
+{
+  "expiration": "2019-08-01T07:15:49",
+  "ref_block_num": 34881,
+  "ref_block_prefix": 2972818865,
+  "max_net_usage_words": 0,
+  "max_cpu_usage_ms": 0,
+  "delay_sec": 0,
+  "context_free_actions": [],
+  "actions": [{
+      "account": "eosio.token",
+      "name": "transfer",
+      "authorization": [{
+          "actor": "han",
+          "permission": "active"
+        }
+      ],
+      "data": {
+        "from": "han",
+        "to": "eosio",
+        "quantity": "0.0001 SYS",
+        "memo": "m"
+      }
+    }
+  ],
+  "transaction_extensions": [
+      {
+        "payer": "sponsoracnt",
+        "max_net_bytes": 4096,
+        "max_cpu_us": 250,
+        "max_memory_bytes": 0
+      }
+  ],
+  "context_free_data": []
+}
+```
+
+### 2. Send the transaction
+
+You can send the transaction you created as JSON snippet in two ways:
+
+* You can send the transaction stored in `TRX_FILE.json` file:
+
+```sh
+cleos push transaction TRX_FILE.json
+```
+
+* Alternatively, you can send the transaction using the JSON content directly:
+
+```sh
+cleos push transaction '{"expiration": "2019-08-01T07:15:49", "ref_block_num": 34881,"ref_block_prefix": 2972818865,"max_net_usage_words": 0,"max_cpu_usage_ms": 0,"delay_sec": 0,"context_free_actions": [],"actions": [{"account": "eosio.token","name": "transfer","authorization": [{"actor": "han","permission": "active"}],"data": {"from": "han","to": "eosio","quantity": "0.0001 SYS","memo": "m"}}],"transaction_extensions": [{"payer": "sponsoracnt",
+"max_net_bytes": 4096,"max_cpu_us": 250,"max_memory_bytes": 0}],"context_free_data": []}'
+```
+
+## Summary
+
+In conclusion, the above instructions show how to submit, or push, a sponsored transaction using the `cleos` CLI tool.