Add project summary in Readme

Author: Frizlab

Readme.adoc

@@ -1,6 +1,10 @@
-= XcodeTools
+= Signal Handling in Swift
 François Lamboley <francois[email protected]>
 
+This package gives you a Swift syntax for the low-level C `sigaction` function,
+and provides a way to delay signals until the registered handlers allow the
+signal to go through.
+
 == Example of Use
 
 I believe good examples are worth thousands of words.