[perl] fix documentation of API authorization in README files (#15356)

align wording across generators

Author: tiffmaelite

modules/openapi-generator/src/main/resources/perl/README.mustache

@@ -312,9 +312,10 @@ Class | Method | HTTP request | Description
 {{/model}}{{/models}}
 
 # DOCUMENTATION FOR AUTHORIZATION
-{{^authMethods}} All endpoints do not require authorization.
-{{/authMethods}}{{#authMethods}}{{#last}} Authentication schemes defined for the API:{{/last}}{{/authMethods}}
-{{#authMethods}}## {{{name}}}
+{{^authMethods}}Endpoints do not require authorization.{{/authMethods}}
+{{#hasAuthMethods}}Authentication schemes defined for the API:{{/hasAuthMethods}}
+{{#authMethods}}
+## {{{name}}}
 
 {{#isApiKey}}- **Type**: API key
 - **API key parameter name**: {{{keyParamName}}}

samples/client/petstore/perl/README.md

@@ -480,6 +480,7 @@ Class | Method | HTTP request | Description
 
 # DOCUMENTATION FOR AUTHORIZATION
 
+Authentication schemes defined for the API:
 ## petstore_auth
 
 - **Type**: OAuth