do-release-upgrade: add page (#3095)

pages/linux/do-release-upgrade.md

@@ -0,0 +1,15 @@
+# do-release-upgrade
+
+> The Ubuntu release upgrader.
+
+- Upgrade to the latest release:
+
+`sudo do-release-upgrade`
+
+- Upgrade to the latest development release:
+
+`sudo do-release-upgrade --devel-release`
+
+- Upgrade to the latest proposed release:
+
+`sudo do-release-upgrade --proposed`