Add update to private networks post

DigitalOcean took a great step forward recently and rolled out actually,
real private networks. This is great and I really hope more companies
realise that shared private networks are a disgrace (cough linode cough)

data/articles/cloud-private-networks.html

@@ -1,3 +1,13 @@
+<div class="note">
+  <div class="note-title">Update 2018-07</div>
+  <div class="note-body">
+    As of July 2018 DigitalOcean <a href="https://www.digitalocean.com/docs/release-notes/2018/private-networking/">has begun rolling out</a>
+    true private networking that is isolated per-account. This is a great step
+    forward, and I sincerely hope other VPS providers follow suit. Until then,
+    this post is still relevant for basically every other provider.
+  </div>
+</div>
+
 <p>
   A while ago I deployed a blog using DigitalOcean's infrastructure. I used
   separate droplets for the database and web tier, and used the "private IP"