docs: update readme for the added speech marks config.

Author: luigel

README.md

@@ -163,7 +163,7 @@ return [
         'polly' => [
             /**
              * Voice ID to use for the synthesis.
-             * You may use any of the following:
+             * You may use any of the following:.
              *
              * Aditi, Amy, Astrid, Bianca, Brian, Camila, Carla, Carmen, Celine,
              * Chantal, Conchita, Cristiano, Dora, Emma, Enrique, Ewa, Filiz,
@@ -175,6 +175,14 @@ return [
              */
             'voice_id' => env('AWS_VOICE_ID', 'Amy'),
 
+            /**
+             * You can request any or all of the speech mark types, but leave it empty if you don't use speech marks.
+             * You may add any of the following:.
+             *
+             * sentence, word, viseme, ssml
+             */
+            'speech_marks' => [],
+
             /**
              * IAM Credentials from AWS.
              */