include: a couple of documentation tweaks and typo fixes.

include/SDL3/SDL_audio.h

@@ -1149,14 +1149,14 @@ extern SDL_DECLSPEC float SDLCALL SDL_GetAudioStreamFrequencyRatio(SDL_AudioStre
  *
  * The frequency ratio is used to adjust the rate at which input data is
  * consumed. Changing this effectively modifies the speed and pitch of the
- * audio. A value greater than 1.0 will play the audio faster, and at a higher
- * pitch. A value less than 1.0 will play the audio slower, and at a lower
- * pitch.
+ * audio. A value greater than 1.0f will play the audio faster, and at a higher
+ * pitch. A value less than 1.0f will play the audio slower, and at a lower
+ * pitch. 1.0f means play at normal speed.
  *
  * This is applied during SDL_GetAudioStreamData, and can be continuously
  * changed to create various effects.
  *
- * \param stream the stream the frequency ratio is being changed.
+ * \param stream the stream on which the frequency ratio is being changed.
  * \param ratio the frequency ratio. 1.0 is normal speed. Must be between 0.01
  *              and 100.
  * \returns true on success or false on failure; call SDL_GetError() for more
@@ -1332,7 +1332,7 @@ extern SDL_DECLSPEC bool SDLCALL SDL_SetAudioStreamInputChannelMap(SDL_AudioStre
  * Channel maps are optional; most things do not need them, instead passing
  * data in the [order that SDL expects](CategoryAudio#channel-layouts).
  *
- * The output channel map reorders data that leaving a stream via
+ * The output channel map reorders data that is leaving a stream via
  * SDL_GetAudioStreamData.
  *
  * Each item in the array represents an input channel, and its value is the