spelling, more explanation

README.md

@@ -1,15 +1,22 @@
 # procmon
 
 procmon is a small Go program for OSX that watches App launch and terminate
-events in AppKit. The Go program directly links against the
+events in AppKit. This project demonstrates the following useful techniques:
+
+- how to call C code from Go with cgo
+- how to link Apple frameworks into a  cgo project
+- how to call Go code from C
+- how to integrate the callback-based concurrency model of AppKit into Go's CSP-style concurrency model
+
+The Go program directly links against the
 [AppKit](https://developer.apple.com/reference/appkit) framework and uses it to
 subscribe to the
 [NSNotificationCenter](https://developer.apple.com/reference/foundation/nsnotificationcenter)
 notifications generated by the OS when the user launches or terminates an App.
-The observer itself is writing in Objective-C. The Objective-C observer is
+The observer itself is written in Objective-C. The Objective-C observer is
-accessed through a simple C function that may be accessed by a Go program. The
+accessed by the Go program through a simple C function. The Objective-C
-Objective-C observer, upon seeing notifications, invokes a Go function
+observer, upon seeing notifications, invokes a Go function directly, passing
-directly, passing control back to our Go program.
+control back to our Go program.
 
 ## installation