doc: reorganize doc tree

With the addition of more HLD documents, the developer-guides index was
getting too busy, so push the HLD documents down a level.

Also, the supported hardware document is buried in the getting started
section and hard to find, so promote it.

Trusty isn't really supported (yet) so drop it from the TOC for now.

Signed-off-by: David B. Kinder <david.b.kinder@intel.com>

doc/developer-guides/ACPI-virt-hld.rst

@@ -1,6 +1,6 @@
 .. _ACPI-virt-HLD:
 
-ACPI Virtualization High Level Design
+ACPI Virtualization high-level design
 #####################################
 
 ACPI introduction

doc/developer-guides/APL_GVT-g-hld.rst

@@ -1,7 +1,7 @@
 .. _APL_GVT-G-hld:
 
-Apollo Lake Intel® GVT-G high-level design
-##########################################
+GVT-G high-level design
+#######################
 
 Introduction
 ************

doc/developer-guides/index.rst

@@ -7,14 +7,22 @@ Developer Guides
    :maxdepth: 1
 
    primer.rst
+   ../api/index.rst
+   ../reference/kconfig/index.rst
+
+High-Level Design Guides
+************************
+
+These documents describe the high-level design, background, and motivation for
+specific areas within the ACRN hypervisor system.
+
+.. toctree::
+   :maxdepth: 1
+
    memmgt-hld.rst
    virtio-hld.rst
    ACPI-virt-hld.rst
    APL_GVT-g-hld.rst
-   ../api/index.rst
-   ../reference/kconfig/index.rst
-   trusty.rst
-
 
 Contributing to the project
 ***************************

doc/developer-guides/memmgt-hld.rst

@@ -1,6 +1,6 @@
 .. _memmgt-hld:
 
-Memory Management High-Level Design
+Memory Management high-level design
 ###################################
 
 This document describes memory management for the ACRN hypervisor.

doc/developer-guides/trusty.rst

@@ -1,3 +1,5 @@
+:orphan:
+
 .. _trusty_tee:
 
 Trusty TEE on ACRN

doc/developer-guides/virtio-hld.rst

@@ -1,6 +1,6 @@
 .. _virtio-hld:
 
-Virtio High Level Design
+Virtio high-level design
 ########################
 
 The ACRN Hypervisor follows the `Virtual I/O Device (virtio)

doc/getting-started/index.rst

@@ -17,6 +17,5 @@ described in :ref:`hardware`. Follow the setup guides listed here:
 .. toctree::
    :maxdepth: 1
 
-   hardware.rst
    apl-nuc.rst
    up2.rst

doc/index.rst

@@ -26,6 +26,7 @@ Sections
 
    introduction/index.rst
    getting-started/index.rst
+   hardware.rst
    user-guides/index.rst
    developer-guides/index.rst
    tutorials/index.rst