[release-branch.go1.12] doc: fix typo in go1.12 release notes

Change-Id: I3cb4fb7cacba51bfd611ade918f16c618e2569fd
Reviewed-on: https://go-review.googlesource.com/c/go/+/172159Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
(cherry picked from commit e47090ab)
Reviewed-on: https://go-review.googlesource.com/c/go/+/172317Reviewed-by: Andrew Bonventre <andybons@golang.org>

doc/go1.12.html

@@ -791,7 +791,7 @@ for {
       A new <a href="/pkg/runtime/debug/#BuildInfo"><code>BuildInfo</code></a> type
       exposes the build information read from the running binary, available only in
       binaries built with module support. This includes the main package path, main
-      module information, and the module dependencies. This type is given though the
+      module information, and the module dependencies. This type is given through the
       <a href="/pkg/runtime/debug/#ReadBuildInfo"><code>ReadBuildInfo</code></a> function
       on <a href="/pkg/runtime/debug/#BuildInfo"><code>BuildInfo</code></a>.
     </p>