Fix doc links to avoid warning on nightly

- one link was just a typo (incorrect `::*`)
- the other one was a wrong intra-link (which are still unstable)

Author: LukasKalbertodt

src/iter/mod.rs

@@ -65,7 +65,7 @@
 //! [`ParallelIterator`]: trait.ParallelIterator.html
 //! [`IndexedParallelIterator`]: trait.IndexedParallelIterator.html
 //! [split]: fn.split.html
-//! [plumbing]: plumbing
+//! [plumbing]: plumbing/index.html
 //!
 //! Note: Several of the `ParallelIterator` methods rely on a `Try` trait which
 //! has been deliberately obscured from the public API.  This trait is intended

src/lib.rs

@@ -48,7 +48,7 @@
 //! parallel implementations of many iterative functions such as [`map`],
 //! [`for_each`], [`filter`], [`fold`], and [more].
 //!
-//! [`rayon::prelude::*`]: prelude/index.html
+//! [`rayon::prelude`]: prelude/index.html
 //! [`map`]: iter/trait.ParallelIterator.html#method.map
 //! [`for_each`]: iter/trait.ParallelIterator.html#method.for_each
 //! [`filter`]: iter/trait.ParallelIterator.html#method.filter