Merge pull request #11 from krzyzanowskim/patch-1

Update README.md

Author: benlangmuir

README.md

@@ -20,5 +20,5 @@ $ swift test
 The C++ code in the index requires `libdispatch`, but unlike Swift code, it cannot find it automatically on Linux. You can work around this by adding a search path manually.
 
 ```sh
-$ swift build -Xcxx -I<path_to_swift_toolchain>/usr/lib/swift
+$ swift build -Xcxx -I<path_to_swift_toolchain>/usr/lib/swift -Xcxx -I<path_to_swift_toolchain>/usr/lib/swift/Block
 ```