docs(cognito): minor clarifications (#13732)

Minor clarification in the docs.

closes #12932
closes #12931
closes #12930


----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

packages/@aws-cdk/aws-cognito/README.md

@@ -87,9 +87,9 @@ new cognito.UserPool(this, 'myuserpool', {
   selfSignUpEnabled: true,
   userVerification: {
     emailSubject: 'Verify your email for our awesome app!',
-    emailBody: 'Hello {username}, Thanks for signing up to our awesome app! Your verification code is {####}',
+    emailBody: 'Thanks for signing up to our awesome app! Your verification code is {####}',
     emailStyle: cognito.VerificationEmailStyle.CODE,
-    smsMessage: 'Hello {username}, Thanks for signing up to our awesome app! Your verification code is {####}',
+    smsMessage: 'Thanks for signing up to our awesome app! Your verification code is {####}',
   }
 });
 ```
@@ -345,7 +345,7 @@ on the construct, as so -
 const authChallengeFn = new lambda.Function(this, 'authChallengeFn', {
   runtime: lambda.Runtime.NODEJS_12_X,
   handler: 'index.handler',
-  code: lambda.Code.fromInline('auth challenge'),
+  code: lambda.Code.fromAsset(/* path to lambda asset */),
 });
 
 const userpool = new cognito.UserPool(this, 'myuserpool', {
@@ -359,7 +359,7 @@ const userpool = new cognito.UserPool(this, 'myuserpool', {
 userpool.addTrigger(cognito.UserPoolOperation.USER_MIGRATION, new lambda.Function(this, 'userMigrationFn', {
     runtime: lambda.Runtime.NODEJS_12_X,
   handler: 'index.handler',
-  code: lambda.Code.fromInline('user migration'),
+  code: lambda.Code.fromAsset(/* path to lambda asset */),
 }));
 ```
 

packages/@aws-cdk/aws-cognito/lib/user-pool-client.ts

@@ -232,7 +232,7 @@ export interface UserPoolClientOptions {
   readonly disableOAuth?: boolean;
 
   /**
-   * OAuth settings for this to client to interact with the app.
+   * OAuth settings for this client to interact with the app.
    * An error is thrown when this is specified and `disableOAuth` is set.
    * @default - see defaults in `OAuthSettings`. meaningless if `disableOAuth` is set.
    */