_content: remove some https://go.dev/ prefixes in links

The site is served at both go.dev and golang.google.cn.
In China, only golang.google.cn can serve, so we try to use
relative links to avoid pointing users to the copy they can't access.

Periodically we have to remove prefixes that have crept in.
This commit applies today's round of that.

Change-Id: Iaa169635664d0562a1cccc57c3e02b687b3493e7
Reviewed-on: https://go-review.googlesource.com/c/website/+/378597
Trust: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: DO NOT USE <katiehockman@google.com>
Trust: DO NOT USE <katiehockman@google.com>

_content/blog/tutorials-go1.18.md

@@ -11,7 +11,7 @@ for Go. We have published two new tutorials to help introduce you to these
 upcoming features.
 
 The first new [tutorial will help you get started with
-generics](https://go.dev/doc/tutorial/generics). This tutorial walks you through
+generics](/doc/tutorial/generics). This tutorial walks you through
 creating a generic function that can handle multiple types, and calling it from
 your code. Once you’ve created a generic function, you’ll learn about type
 constraints, and write some for your function. Also consider checking out the
@@ -19,21 +19,21 @@ constraints, and write some for your function. Also consider checking out the
 generics](https://www.youtube.com/watch?v=35eIxI_n5ZM&t=1755s) to learn more.
 
 The second new [tutorial will help you get started with
-fuzzing](https://go.dev/doc/tutorial/fuzz). This tutorial demonstrates how
+fuzzing](/doc/tutorial/fuzz). This tutorial demonstrates how
 fuzzing can find bugs in your code, and walks through the process of diagnosing
 and fixing the issues. In this tutorial, you will write code that has a few bugs
 and use fuzzing to find, fix, and verify the bugs using the go command. Special
 thanks to Beth Brown for her work on the fuzzing tutorial!
 
 Go 1.18 Beta 1 was released last month, which you can get by visiting the
-[downloads page](https://go.dev/dl/#go1.18beta1).
+[downloads page](/dl/#go1.18beta1).
 
 See the full [draft release notes for Go
 1.18](https://tip.golang.org/doc/go1.18) for more details about what to expect
 in the release.
 
 As always, if you notice any problems, please [file an
-issue](https://go.dev/issue/new).
+issue](/issue/new).
 
 We hope you enjoy the tutorials, and we look forward to everything to come in
 2022!

_content/doc/fuzz/index.md

@@ -220,7 +220,7 @@ $ file2fuzz
 
 - **Tutorial**:
   - For an introductory tutorial of fuzzing with Go, please see [the blog
-    post](https://go.dev/blog/fuzz-beta).
+    post](/blog/fuzz-beta).
   - More to come soon!
 - **Documentation**:
   - The [`testing`](https://pkg.go.dev//testing#hdr-Fuzzing) package docs

_content/doc/tutorial/fuzz.md

@@ -458,7 +458,7 @@ However, characters such as 泃 can require several bytes. Thus, reversing the
 string byte-by-byte will invalidate multi-byte characters.
 
 **Note:** If you’re curious about how Go deals with strings, read the blog post
-[Strings, bytes, runes and characters in Go](https://go.dev/blog/strings) for a
+[Strings, bytes, runes and characters in Go](/blog/strings) for a
 deeper understanding.
 
 With a better understanding of the bug, correct the error in the `Reverse`
@@ -537,7 +537,7 @@ would be a great approach.
 In this tutorial, we will log useful debugging info in the `Reverse` function.
 
 Look closely at the reversed string to spot the error. In Go, [a string is a
-read only slice of bytes](https://go.dev/blog/strings), and can contain bytes
+read only slice of bytes](/blog/strings), and can contain bytes
 that aren’t valid UTF-8. The original string is a byte slice with one byte,
 `'\x91'`. When the input string is set to rune[], Go encodes the byte slice to
 UTF-8, and replaces the byte with the UTF-8 character <20>. When we compare the

_content/doc/tutorial/generics.md

@@ -22,7 +22,7 @@ You'll progress through the following sections:
 **Note:** For other tutorials, see [Tutorials](/doc/tutorial/index.html).
 
 **Note:** If you prefer, you can use
-[the Go playground in “Go dev branch” mode](https://go.dev/play/?v=gotip)
+[the Go playground in “Go dev branch” mode](/play/?v=gotip)
 to edit and run your program instead.
 
 ## Prerequisites
@@ -484,7 +484,7 @@ Suggested next topics:
 
 <!--TODO: Update text and link after release.-->
 You can run this program in the
-[Go playground](https://go.dev/play/p/apNmfVwogK0?v=gotip). On the
+[Go playground](/play/p/apNmfVwogK0?v=gotip). On the
 playground simply click the **Run** button.
 
 ```

_content/tour/concurrency.article

@@ -186,17 +186,17 @@ If you need help with the standard library, see the [[/pkg/][package reference]]
 
 To further explore Go's concurrency model, watch
 [[https://www.youtube.com/watch?v=f6kdp27TYZs][Go Concurrency Patterns]]
-([[https://go.dev/talks/2012/concurrency.slide][slides]])
+([[/talks/2012/concurrency.slide][slides]])
 and
 [[https://www.youtube.com/watch?v=QDDwwePbDtw][Advanced Go Concurrency Patterns]]
-([[https://go.dev/talks/2013/advconc.slide][slides]])
+([[/talks/2013/advconc.slide][slides]])
 and read the
 [[/doc/codewalk/sharemem/][Share Memory by Communicating]]
 codewalk.
 
 To get started writing web applications, watch
 [[https://vimeo.com/53221558][A simple programming environment]]
-([[https://go.dev/talks/2012/simple.slide][slides]])
+([[/talks/2012/simple.slide][slides]])
 and read the
 [[/doc/articles/wiki/][Writing Web Applications]] tutorial.