Add Elevenlabs docs for running binary examples

Author: chr-hertel

examples/elevenlabs/README.md

@@ -0,0 +1,9 @@
+# Elevenlabs Examples
+
+One use case of Elevenlabs is to convert text to speech, which creates audio files from text input.
+
+To run the examples, you can use additional tools like (mpg123)[https://www.mpg123.de/]:
+
+```bash
+php elevenlabs/text-to-speech.php | mpg123 -
+```