docs(nix-compat): fix some docstring references

Change-Id: Ic1b3148f549d8d41a00b5a17f360cc7074fe30ae
Reviewed-on: https://cl.tvl.fyi/c/depot/+/13248
Tested-by: BuildkiteCI
Autosubmit: flokli <flokli@flokli.de>
Reviewed-by: Domen Kožar <domen@cachix.org>
Reviewed-by: Marijan Petričević <marijan.petricevic94@gmail.com>

tvix/nix-compat/src/store_path/mod.rs

@@ -172,7 +172,7 @@ where
         }
     }
 
-    /// Decompose a string into a [StorePath] and a [PathBuf] containing the
+    /// Decompose a string into a [StorePath] and a [Path] containing the
     /// rest of the path, or an error.
     #[cfg(target_family = "unix")]
     pub fn from_absolute_path_full<'a, P>(path: &'a P) -> Result<(Self, &'a Path), Error>