[x/blog] content/versioning-proposal: fix year of gophercon discussion
[x/blog] content/versioning-proposal: fix year of gophercon discussion

The versioning discussions happened at Gophercon 2016, not 2015.

Change-Id: I80236f9f364f080daf0e46a487cab92e71a18a0c
Reviewed-on: https://go-review.googlesource.com/109655
Run-TryBot: Russ Cox <5ad239cb8a44f659eaaee0aa1ea5b94947abe557@golang.org>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>
X-Blog-Commit: 375ae503c1a6e1c8bb52c4548e8570a4a95e897f

golang/website,golang/website,golang/website,golang/website,golang/website,golang/website,golang/website