More spelling corrections.

src/libstd/rt/io/extensions.rs

@@ -262,7 +262,7 @@ pub trait WriterByteConversions {
     /// (8 bytes).
     fn write_le_f64(&mut self, f: f64);
 
-    /// Write a litten-endian IEEE754 single-precision floating-point
+    /// Write a little-endian IEEE754 single-precision floating-point
     /// (4 bytes).
     fn write_le_f32(&mut self, f: f32);
 

src/libstd/rt/io/mod.rs

@@ -430,7 +430,7 @@ pub trait Reader {
     ///         println(reader.read_line());
     ///     }
     ///
-    /// # Failue
+    /// # Failure
     ///
     /// Returns `true` on failure.
     fn eof(&mut self) -> bool;