A couple of small doc tweaks

CONTRIBUTING.md

@@ -55,6 +55,9 @@ Once you're ready to start programming, have a read of the [the architecture doc
 not a comprehensive document, it gives a good hint of where you should start looking to make your changes. As always, if
 you're not sure, [do ask the community][community]!
 
+Generative AI contributions are *not* welcome. PRs containing, or suspected of containing, code output by a generative
+AI model will be immediately rejected.
+
 ### Testing
 When making larger changes, it may be useful to write a test to make sure your code works as expected.
 

doc/guides/speaker_audio.md

@@ -51,7 +51,7 @@ speaker.playAudio(buffer)
 ```
 
 ## Streaming audio
-You might notice that the above snippet only generates a short bit of audio - 2.7s seconds to be precise. While we could
+You might notice that the above snippet only generates a short bit of audio - a little over 2.7 seconds. While we could
 try increasing the number of loop iterations, we'll get an error when we try to play it through the speaker: the sound
 buffer is too large for it to handle.