Update docfx (#13679)

build/azure-pipelines.yml

@@ -147,7 +147,7 @@ stages:
             inputs:
               targetType: inline
               script: |
-                choco install docfx --version=2.59.2 -y
+                choco install docfx --version=2.59.4 -y
                 if ($lastexitcode -ne 0){
                     throw ("Error installing DocFX")
                 }