_content/doc/tutorial: remove mention of init function

the init function is removed from the code example: f7341273fe

Change-Id: Id247fed6f46ad83e47c9871519ed8001dca79c62
GitHub-Last-Rev: 012feea9eb
GitHub-Pull-Request: golang/website#230
Reviewed-on: https://go-review.googlesource.com/c/website/+/507096
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Hyang-Ah Hana Kim <hyangah@gmail.com>
Reviewed-by: Robert Findley <rfindley@google.com>

_content/doc/tutorial/random-greeting.html

@@ -91,13 +91,6 @@ func randomFormat() string {
         >
         to generate a random number for selecting an item from the slice.
       </li>
-      <li>
-        Add an <code>init</code> function to seed the <code>rand</code> package
-        with the current time. Go executes <code>init</code> functions
-        automatically at program startup, after global variables have been
-        initialized. For more about <code>init</code> functions, see
-        <a href="/doc/effective_go.html#init">Effective Go</a>.
-      </li>
       <li>
         In <code>Hello</code>, call the <code>randomFormat</code> function to
         get a format for the message you'll return, then use the format and