Rollup merge of #133419 - CromFr:add-path-strip_prefix-test-example, r=Amanieu

Added a doc test for std::path::strip_prefix

I was about 90% sure `Path::new("/test/haha/foo.txt").strip_prefix("/te")` would return an Err, but I couldn't find an example to confirm this behaviour.

This should be an easy merge :)

library/std/src/path.rs

@@ -2504,6 +2504,7 @@ impl Path {
     /// assert_eq!(path.strip_prefix("/test/haha/foo.txt/"), Ok(Path::new("")));
     ///
     /// assert!(path.strip_prefix("test").is_err());
+    /// assert!(path.strip_prefix("/te").is_err());
     /// assert!(path.strip_prefix("/haha").is_err());
     ///
     /// let prefix = PathBuf::from("/test/");