doc/install.html: address comments from review of previous edit

Point out that one can just run the commands now; it's not necessary
to log out first.

Change-Id: I48d0cc0273d97ba54ce59b3a3bbcae0b5af9aaef
Reviewed-on: https://go-review.googlesource.com/106195Reviewed-by: Ian Lance Taylor <iant@golang.org>

doc/install.html

@@ -108,8 +108,10 @@ export PATH=$PATH:/usr/local/go/bin
 
 <p>
 <b>Note</b>: changes made to a <code>profile</code> file may not apply until the
-next time you log into your computer. Alternatively, you can apply them to the
-current shell with a command like <code>source $HOME/.profile</code>.
+next time you log into your computer.
+To apply the changes immediately, just run the shell commands directly
+or execute them from the profile using a command such as
+<code>source $HOME/.profile</code>.
 </p>
 
 <h4 id="tarball_non_standard">Installing to a custom location</h4>