Add link to android_binary_size_trybot.md from README.md

TBR=agrieve  # Doc update

Change-Id: Ic95a3f76b59dbf051d41f4470ec87e9983fbf866
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1992113Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Reviewed-by: Mohamed Heikal <mheikal@chromium.org>
Commit-Queue: Andrew Grieve <agrieve@chromium.org>
Auto-Submit: Andrew Grieve <agrieve@chromium.org>
Cr-Commit-Position: refs/heads/master@{#729775}

tools/binary_size/README.md

@@ -23,10 +23,7 @@ Per-Milestone Binary Size Breakdowns:
 ## Binary Size Trybot (android-binary-size)
 
  * Introduced October 2018 as a mandatory CQ bot.
- * Example builds: https://ci.chromium.org/p/chromium/builders/luci.chromium.try/android-binary-size
- * Provides size per-patch size analysis via `resource_sizes.py` and SuperSize.
- * Forces a `Binary-Size:` footer to be present for commits that are larger than
-   16KiB (autorollers exempted).
+ * Documented [here](/docs/speed/binary_size/android_binary_size_trybot.md).
 
 ## Binary Size Gerrit Plugin