auto merge of #14357 : huonw/rust/spelling, r=pnkfelix

The span on a inner doc-comment would point to the next token, e.g. the span for the `a` line points to the `b` line, and the span of `b` points to the `fn`.

```rust
//! a
//! b

fn bar() {}
```

src/libstd/io/process.rs

@@ -123,7 +123,7 @@ impl Command {
     /// * Inherit the current process's environment
     /// * Inherit the current process's working directory
     /// * A readable pipe for stdin (file descriptor 0)
-    /// * A writeable pipe for stdour and stderr (file descriptors 1 and 2)
+    /// * A writeable pipe for stdout and stderr (file descriptors 1 and 2)
     ///
     /// Builder methods are provided to change these defaults and
     /// otherwise configure the process.