Auto merge of rust-lang#34590 - pwlandoll:master, r=apasel422

Issue rust-lang#34076: Removing reference to removed path.prefix() function

In the documentation for `std::path::Path`, there is a [reference](https://doc.rust-lang.org/std/path/struct.Path.html#method.is_absolute) to the `path.prefix()` function which has since been removed. The offending reference is now also removed.

First pull request, feedback welcome!

r? @steveklabnik

Author: bors

src/libstd/path.rs

@@ -1442,8 +1442,7 @@ impl Path {
     /// `is_absolute` and `has_root` are equivalent.
     ///
     /// * On Windows, a path is absolute if it has a prefix and starts with the
-    /// root: `c:\windows` is absolute, while `c:temp` and `\temp` are not. In
-    /// other words, `path.is_absolute() == path.prefix().is_some() && path.has_root()`.
+    /// root: `c:\windows` is absolute, while `c:temp` and `\temp` are not.
     ///
     /// # Examples
     ///