doc/effective_go.html: remove spurious word
Fixes #6003.
R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/12387045
diff --git a/doc/effective_go.html b/doc/effective_go.html
index 1ca9bd5..8c66fa24 100644
--- a/doc/effective_go.html
+++ b/doc/effective_go.html
@@ -2560,7 +2560,7 @@
it actually satisfies the interface.
If a type—for example,
<code><a href="/pkg/encoding/json/#RawMessage">json.RawMessage</a></code>—needs
-a custom its JSON representation, it should implement
+a custom JSON representation, it should implement
<code>json.Marshaler</code>, but there are no static conversions that would
cause the compiler to verify this automatically.
If the type inadvertently fails to satisfy the interface, the JSON encoder will still work,
