docs: build the Hafnium Hypervisor documentation

The Hafnium Hypervisor documentation is kept as a legacy provided this
component is still used for test purposes within the Hafnium CI.

As the original files are .md files as opposed to .rst files for the
remaining of the project, adjust tags to permit building with sphinx.

Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
Change-Id: I5fc138cf7bc2de1276823c0739cbca6d136f26dd
diff --git a/docs/hypervisor/index.rst b/docs/hypervisor/index.rst
new file mode 100644
index 0000000..7531076
--- /dev/null
+++ b/docs/hypervisor/index.rst
@@ -0,0 +1,26 @@
+Hypervisor
+==========
+
+.. note::
+
+   Following sections cover the legacy Hafnium Hypervisor implementation.
+   As a disclaimer, the Hypervisor is maintained as a legacy component used for
+   test purposes in the Hafnium CI. It shall not be used to build a product and
+   the support is not guaranteed.
+
+.. toctree::
+   :maxdepth: 1
+
+   GetStarted
+   Architecture
+   CodeStructure
+   FVP
+   HafniumRamDisk
+   HermeticBuild
+   Maintainers
+   Manifest
+   PreparingLinux
+   SchedulerExpectations
+   StyleGuide
+   Testing
+   VmInterface