_content/doc: fix gitconfig typo

Fixes golang/go#45691

Change-Id: I6ad64a06853d153f90636583abede168573b89b6
Reviewed-on: https://go-review.googlesource.com/c/website/+/313189
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Cherry Zhang <cherryyz@google.com>
diff --git a/_content/doc/mod.md b/_content/doc/mod.md
index f8665d7..c2faf26 100644
--- a/_content/doc/mod.md
+++ b/_content/doc/mod.md
@@ -3031,7 +3031,7 @@
 in `.gitconfig`:
 
 ```
-[url "git@github.com:']
+[url "git@github.com:"]
     insteadOf = https://github.com/
 ```