_content/doc/tutorial: remove use of deprecated math/rand.Seed

Fixes golang/go#58958

Change-Id: I5ef84f2fd350e3048649cf281e8272e62b2fc052
Reviewed-on: https://go-review.googlesource.com/c/website/+/475275
Run-TryBot: Bryan Mills <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>
Auto-Submit: Ian Lance Taylor <[email protected]>
Run-TryBot: Ian Lance Taylor <[email protected]>
Reviewed-by: Bryan Mills <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>

Author: seankhliao

_content/doc/tutorial/greetings-multiple-people.html

@@ -73,11 +73,6 @@
     return messages, nil
 }</ins>
 
-// Init sets initial values for variables used in the function.
-func init() {
-    rand.Seed(time.Now().UnixNano())
-}
-
 // randomFormat returns one of a set of greeting messages. The returned
 // message is selected at random.
 func randomFormat() string {

_content/doc/tutorial/random-greeting.html

@@ -51,12 +51,7 @@
     return message, nil
 }
 
-<ins>// init sets initial values for variables used in the function.
-func init() {
-    rand.Seed(time.Now().UnixNano())
-}
-
-// randomFormat returns one of a set of greeting messages. The returned
+<ins>// randomFormat returns one of a set of greeting messages. The returned
 // message is selected at random.
 func randomFormat() string {
     // A slice of message formats.