fix(readme.md): specify use of public key as authorization

Author: thecodecafe

README.md

@@ -94,7 +94,7 @@ import {PayWithFlutterwave} from 'flutterwave-react-native';
   onRedirect={handleOnRedirect}
   options={{
     tx_ref: transactionReference,
-    authorization: '[merchant secret key]',
+    authorization: '[merchant public key]',
     customer: {
       email: 'customer-email@example.com'
     },
@@ -159,7 +159,7 @@ try {
   // initialize payment
   const paymentLink = await FlutterwaveInit({
     tx_ref: generateTransactionRef(),
-    authorization: '[your merchant secret Key]',
+    authorization: '[your merchant public Key]',
     amount: 100,
     currency: 'USD',
     customer: {
@@ -183,7 +183,7 @@ try {
 [See Interface](#flutterwaveinitoptions-interface)
 | Name     | Required | Type | Default | Description |
 | --------- | --------- | ---- | ------- | ----------- |
-| authorization | Yes | string | **REQUIRED** | Your merchant secret key, see how to get your [API Keys](https://developer.flutterwave.com/v3.0/docs/api-keys)|
+| authorization | Yes | string | **REQUIRED** | Your merchant public key, see how to get your [API Keys](https://developer.flutterwave.com/v3.0/docs/api-keys)|
 | tx_ref | Yes | string | **REQUIRED** | Your transaction reference. This MUST be unique for every transaction.|
 | amount | Yes | string | **REQUIRED** | Amount to charge the customer. |
 | currency | No | string | NGN | Currency to charge in. Defaults to NGN. |