Add DifferentiationInterface logo (#220)

Author: adrhill

DifferentiationInterface/README.md

@@ -1,3 +1,5 @@
+![DifferentiationInterface Logo](https://raw.githubusercontent.com/gdalle/DifferentiationInterface.jl/DifferentiationInterface/docs/src/assets/logo.svg)
+
 # DifferentiationInterface
 
 [![Build Status](https://github.com/gdalle/DifferentiationInterface.jl/actions/workflows/CI.yml/badge.svg?branch=main)](https://github.com/gdalle/DifferentiationInterface.jl/actions/workflows/CI.yml?query=branch%3Amain)

DifferentiationInterface/docs/make.jl

@@ -40,7 +40,7 @@ makedocs(;
     modules=[DifferentiationInterface, ADTypes, extensions...],
     authors="Guillaume Dalle, Adrian Hill",
     sitename="DifferentiationInterface.jl",
-    format=Documenter.HTML(),
+    format=Documenter.HTML(; assets=["assets/favicon.ico"]),
     pages=[
         "Home" => "index.md",
         "Start here" => ["tutorial.md", "overview.md", "backends.md"],