 doc/articles/wiki: add missing log import to net/http tutorial
 doc/articles/wiki: add missing log import to net/http tutorial

The log package is used with the net/http but was not in the import clause.

Change-Id: Ic45b987633adf0ee15defd4d136b5d37027e22b0
GitHub-Last-Rev: e74aff53370569864b7ec8c18617a5d992d34bf2
GitHub-Pull-Request: golang/go#36674
Reviewed-on: https://go-review.googlesource.com/c/go/+/215618
Reviewed-by: Emmanuel Odeke <277f8eaa8c7dfbc55c17bf5e30561c1a9c45c569@gmail.com>

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