Correct Swift/Xcode/OS minimum/recommended versions.

README.md

@@ -19,25 +19,25 @@ Swift cross-platform RSA wrapper library for RSA encryption and signing. Works o
 
 ### Swift
 
-* Swift Open Source `swift-3.0.1-RELEASE` toolchain (**Minimum REQUIRED for latest release**)
-* Swift Open Source `swift-4.0.0-RELEASE` toolchain (**Recommended**)
+* Swift Open Source `swift-4.0.0-RELEASE` toolchain (**Minimum REQUIRED for latest release**)
+* Swift Open Source `swift-4.0.3-RELEASE` toolchain (**Recommended**)
 * Swift toolchain included in *Xcode Version 9.0 (9A325) or higher*.
 
 ### macOS
 
-* macOS 10.11.6 (*El Capitan*) or higher
-* Xcode Version 8.3.2 (8E2002) or higher using one of the above toolchains (*Recommended*)
-* Xcode Version 9.0 (9A325) or higher using the included toolchain.
+* macOS 10.12.0 (*Sierra*) or higher
+* Xcode Version 9.0 (9A325) or higher using the included toolchain (**Minimum REQUIRED for latest release**).
+* Xcode Version 9.2 (9C40b) or higher using the included toolchain (**Recommended**).
 
 ### iOS
 
 * iOS 10.0 or higher
-* Xcode Version 8.3.2 (8E2002) or higher using one of the above toolchains (*Recommended*)
-* Xcode Version 9.0 (9A325) or higher using the included toolchain.
+* Xcode Version 9.0 (9A325) or higher using the included toolchain (**Minimum REQUIRED for latest release**).
+* Xcode Version 9.2 (9C40b) or higher using the included toolchain (**Recommended**).
 
 ### Linux
 
-* **Linux Support forthcoming.**
+* **Work in progress**
 * Ubuntu 16.04 (or 16.10 but only tested on 16.04)
 * One of the Swift Open Source toolchains listed above