[x/tour] tour: add Italian translation.
[x/tour] tour: add Italian translation.

Change-Id: I387f441ace958b770630da2ac81dbe17a91fe6fc
Reviewed-on: https://go-review.googlesource.com/7042
Reviewed-by: Andrew Gerrand <395a7d33bec8475c9b83b7d440f141bcbd994aa5@golang.org>
X-Tour-Commit: 6102c36a7de5709ee1fadfbca7eda60958dc183c

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