Address some nits highlighted by ishitatsuyuki

src/host/coreaudio/mod.rs

@@ -93,7 +93,7 @@ impl HostTrait for Host {
     type EventLoop = EventLoop;
 
     fn is_available() -> bool {
-        // Assume ALSA is always available on linux/freebsd.
+        // Assume coreaudio is always available on macOS and iOS.
         true
     }
 

src/host/emscripten/mod.rs

@@ -41,7 +41,7 @@ impl HostTrait for Host {
     type EventLoop = EventLoop;
 
     fn is_available() -> bool {
-        // Assume ALSA is always available on linux/freebsd.
+        // Assume this host is always available on emscripten.
         true
     }
 

src/lib.rs

@@ -171,7 +171,7 @@ mod samples_formats;
 ///
 /// Another great example is the Linux platform. While the ALSA host API is the lowest-level API
 /// available to almost all distributions of Linux, its flexibility is limited as it requires that
-/// each process have exclusive access to the devices with which they establish streams. PortAudio
+/// each process have exclusive access to the devices with which they establish streams. PulseAudio
 /// is another popular host API that aims to solve this issue by providing user-space mixing,
 /// however it has its own limitations w.r.t. low-latency and high-performance audio applications.
 /// JACK is yet another host API that is more suitable to pro-audio applications, however it is