Correct documentation about starting code-review

The button says "START REVIEW" these days.

Change-Id: Ia285ce8b0b7f8d6698f31e070c60e99f8ffacb8e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2043814
Auto-Submit: Fredrik Söderquist <[email protected]>
Reviewed-by: Stephen Chenney <[email protected]>
Commit-Queue: Stephen Chenney <[email protected]>
Cr-Commit-Position: refs/heads/master@{#739406}
diff --git a/docs/contributing.md b/docs/contributing.md
index 145b014..1509632 100644
--- a/docs/contributing.md
+++ b/docs/contributing.md
@@ -233,8 +233,8 @@
 
 In the same dialog, you can include an optional message to your reviewers. This
 space can be used for specific questions or instructions. Once you're done,
-make sure to click **Send**, which notifies the requested reviewers that they
-should review your change.
+make sure to click **Start Review**, which notifies the requested reviewers that
+they should review your change.
 
 **IMPORTANT: UNTIL YOU SEND THE REVIEW REQUEST, NO ONE WILL LOOK AT THE REVIEW**