Remove Enginio from Qt Add-Ons listing

We've been removing the module from Qt already in Qt 5.7.
With commit 05135158

 we removed almost all traces
of Qt Cloud Services and Enginio, except for the "All Modules"
and "What's New in Qt 5.3" pages.

This patch now removes Enginio also from All Modules.

Change-Id: Iefd5006f5ee9e52c519c702e44ad9f9112b09883
Reviewed-by: Venugopal Shivashankar <Venugopal.Shivashankar@qt.io>

doc/src/qtmodules.qdoc

@@ -142,12 +142,6 @@
          \li
          \li Functionality for near-realtime simulation systems with support
              for 2D and 3D rendering.
-    \row
-        \li \l{Enginio Manual}{Enginio} (Deprecated)
-        \li All
-        \li All
-        \li A Backend-as-a-Service solution to ease the backend development for
-            connected and data-driven applications.
     \row
         \li \l[QtAndroidExtras]{Qt Android Extras}
         \li All