x/website: correct a small grammatical error at effective_go page

Change-Id: Ia58d129bb7d71adad62d77a8347392ea11d8c9e0
GitHub-Last-Rev: f085d0163304b8762a93ee3ffb66f511b00a6b96
GitHub-Pull-Request: golang/website#75
Reviewed-on: https://go-review.googlesource.com/c/website/+/336869
Reviewed-by: Rob Pike <r@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Trust: Rob Pike <r@golang.org>
diff --git a/_content/doc/effective_go.html b/_content/doc/effective_go.html
index f2f056d..519fbd4 100644
--- a/_content/doc/effective_go.html
+++ b/_content/doc/effective_go.html
@@ -156,7 +156,7 @@
 package.
 Comments that appear before top-level declarations, with no intervening newlines,
 are extracted along with the declaration to serve as explanatory text for the item.
-The nature and style of these comments determines the
+The nature and style of these comments determine the
 quality of the documentation <code>godoc</code> produces.
 </p>