Style guide: The source code has moved; update link to match

Bug: none
Change-Id: I89a8451f36fe159ad18d0083ac3ce38004973d80
Notry: true
Reviewed-on: https://webrtc-review.googlesource.com/61721
Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
Commit-Queue: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#22422}

style-guide.md

diff --git a/style-guide.md b/style-guide.md
index d8fbaae..8782ff1 100644
--- a/style-guide.md
+++ b/style-guide.md
@@ -34,7 +34,7 @@
 `const T* ptr, size_t num_elements` | `ArrayView<const T>`
 `T* ptr, size_t num_elements`       | `ArrayView<T>`
 
-See [the source](webrtc/api/array_view.h) for more detailed docs.
+See [the source](api/array_view.h) for more detailed docs.
 
 ### sigslot