Add nuget metadata;

Add NuGet reference in README.

Author: Denis Ivanov

README.md

@@ -1,3 +1,4 @@
-XPath support for AngleSharp
+# AngleSharp.XPath
 
 [![Build Status](https://travis-ci.org/denis-ivanov/AngleSharp.XPath.svg?branch=master&style=flat-square)](https://travis-ci.org/denis-ivanov/AngleSharp.XPath)
+[![NuGet](http://img.shields.io/nuget/v/AngleSharp.XPath.svg)](https://www.nuget.org/packages/AngleSharp.XPath/)

src/AngleSharp.XPath/AngleSharp.XPath.csproj

@@ -1,4 +1,14 @@
 <Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <Version>1.0.0</Version>
+    <Authors>Denis Ivanov</Authors>
+    <PackageId>AngleSharp.XPath</PackageId>
+    <AssemblyVersion>1.0.0</AssemblyVersion>
+    <FileVersion>1.0.0</FileVersion>
+    <Description>XPath support for AngleSharp</Description>
+    <PackageProjectUrl>https://github.com/denis-ivanov/AngleSharp.XPath/</PackageProjectUrl>
+    <PackageTags>HTML XPath AngleSharp</PackageTags>
+  </PropertyGroup>
   <PropertyGroup>
     <TargetFramework>netstandard2.0</TargetFramework>
   </PropertyGroup>