fix typo (still -> install) (#904)

examples/ios-feedback/README.md

@@ -5,7 +5,7 @@ audio streams. Audio samples are read in from your microphone and then
 routed to your audio output device with a small but noticeable delay,
 so you can verify it is working correctly.
 
-To build the example you will need to still `cargo-lipo`. While not
+To build the example you will need to install `cargo-lipo`. While not
 necessary for building iOS binaries, it is used to build a universal
 binary (x86 for simulator and aarch64 for device.)