README: fix doc links

Change-Id: Iffbb35cdda9de495b0612a545893d1b7d5e3cb13
Reviewed-on: https://chromium-review.googlesource.com/1168452Reviewed-by: Ryan Tseng <hinoka@chromium.org>
Reviewed-by: Patrik Höglund <phoglund@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>

README.md

@@ -10,9 +10,9 @@
 
 ### Development
 
-See [Getting started] [1] for instructions on how to get started developing.
+See [Getting started][1] for instructions on how to get started developing.
 
-You can also browse the [docs directory] [2] for more documentation.
+You can also browse the [docs directory][2] for more documentation.
 
-[1]: https://chromium.googlesource.com/libyuv/libyuv/+/master/docs/getting_started.md
-[2]: https://chromium.googlesource.com/libyuv/libyuv/+/master/docs/
+[1]: ./docs/getting_started.md
+[2]: ./docs/