doc/go1.19: fix a few links that were missing trailing slashes
doc/go1.19: fix a few links that were missing trailing slashes

They were part of a chain of three redirects. Now it's only two,
but that's #54081.

Change-Id: Ibfe6a17a372df61df40124892951b48577e4ced9
Reviewed-on: https://go-review.googlesource.com/c/go/+/419634
Run-TryBot: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>
Reviewed-by: Dmitri Shuralyov <d181b7fea0ec87c86ba5a890ab716db52498e3ba@google.com>
Auto-Submit: Dmitri Shuralyov <d181b7fea0ec87c86ba5a890ab716db52498e3ba@golang.org>
Reviewed-by: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@google.com>
TryBot-Result: Gopher Robot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>

golang/go,golang/go,golang/go,golang/go,golang/go,golang/go,golang/go,golang/go