doc, cmd/go: adjust documentation for default GOPATH

Replaces CL 33356.

Fixes #17262.

Change-Id: Idfb2343e90771775e51a66c63760f458737a288c
Reviewed-on: https://go-review.googlesource.com/33730
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
diff --git a/doc/install-source.html b/doc/install-source.html
index 22cc1d5..4a25e37 100644
--- a/doc/install-source.html
+++ b/doc/install-source.html
@@ -430,7 +430,7 @@
 <ul>
 <li><code>$GOROOT</code>
 <p>
-The root of the Go tree, often <code>$HOME/go</code>.
+The root of the Go tree, often <code>$HOME/go1.X</code>.
 Its value is built into the tree when it is compiled, and
 defaults to the parent of the directory where <code>all.bash</code> was run.
 There is no need to set this unless you want to switch between multiple
@@ -632,7 +632,7 @@
 </p>
 
 <pre>
-export GOROOT=$HOME/go
+export GOROOT=$HOME/go1.X
 export GOARCH=amd64
 export GOOS=linux
 </pre>