os: use same link in UserCacheDir/UserConfigDir doc

Change-Id: I94c385243c37589f56aadaa30336b400adf31308
Reviewed-on: https://go-review.googlesource.com/c/go/+/234959
Reviewed-by: Ian Lance Taylor <iant@golang.org>
diff --git a/src/os/file.go b/src/os/file.go
index 93ba4d7..a2b71cb 100644
--- a/src/os/file.go
+++ b/src/os/file.go
@@ -384,7 +384,7 @@
 // within this one and use that.
 //
 // On Unix systems, it returns $XDG_CACHE_HOME as specified by
-// https://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html if
+// https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html if
 // non-empty, else $HOME/.cache.
 // On Darwin, it returns $HOME/Library/Caches.
 // On Windows, it returns %LocalAppData%.