IVGCVSW-3726 Doxygen touch-up

 * Doxygen comment touch-ups
 * Fixed markup in .dox files
 * Fixed stylesheet
 * Doxyfile changes
 * Added logo file
 * Added header file

Signed-off-by: Ryan OShea <Ryan.OShea2@arm.com>
Change-Id: I94c7f5a6923a0bbb5c6ed610f1f55d57e2bb8a49
diff --git a/include/armnn/backends/IBackendInternal.hpp b/include/armnn/backends/IBackendInternal.hpp
index 6ad9bba..6771e7b 100644
--- a/include/armnn/backends/IBackendInternal.hpp
+++ b/include/armnn/backends/IBackendInternal.hpp
@@ -68,18 +68,18 @@
 class IBackendInternal : public IBackend
 {
 protected:
-    // Creation must be done through a specific
-    // backend interface.
+    /// Creation must be done through a specific
+    /// backend interface.
     IBackendInternal() = default;
 
 public:
-    // Allow backends created by the factory function
-    // to be destroyed through IBackendInternal.
+    /// Allow backends created by the factory function
+    /// to be destroyed through IBackendInternal.
     ~IBackendInternal() override = default;
 
     using IWorkloadFactoryPtr = std::unique_ptr<IWorkloadFactory>;
     using IBackendContextPtr = std::unique_ptr<IBackendContext>;
-    // This is the bridge between backend and backend profiling we'll keep it in the backend namespace.
+    /// This is the bridge between backend and backend profiling we'll keep it in the backend namespace.
     using IBackendProfilingContextPtr = std::shared_ptr<armnn::profiling::IBackendProfilingContext>;
     using IBackendProfilingPtr = std::unique_ptr<armnn::profiling::IBackendProfiling>;
     using OptimizationPtr = std::unique_ptr<Optimization>;