Fixed typo

Author: fzhinkin

README.md

@@ -22,7 +22,7 @@ The library also provides interfaces representing data sources and destinations
 In addition to `Buffer`, the library provides an immutable sequence of bytes - `ByteString`.
 
 Also, there's an experimental filesystem support provided by `kotlinx.io.files` package. 
-The package includes `FileSystem` interface  and its implementation - `SystemFileSystem`. 
+The package includes `FileSystem` interface and its implementation - `SystemFileSystem`. 
 
 `FileSystem` provides basic operations for working with files and directories.