Added documentation on cross-solution configuration.

Author: ngeor

documentation/Configuration.md

@@ -390,7 +390,7 @@ The following properties are used to configure copyright headers in StyleCop Ana
 | `copyrightText` | `"Copyright (c) {companyName}. All rights reserved."` | 1.0.0 | Specifies the default copyright text which should appear in copyright headers |
 | `xmlHeader` | **true** | 1.0.0 | Specifies whether file headers should use standard StyleCop XML format, where the copyright notice is wrapped in a `<copyright>` element |
 | `variables` | n/a | 1.0.0 | Specifies replacement variables which can be referenced in the `copyrightText` value |
-| `headerDecoration` | n/a | 1.1.0 | This value can be set to add a decoration for the header comment so headers look similar to the ones generated by the StyleCop Classic ReSharper fix | 
+| `headerDecoration` | n/a | 1.1.0 | This value can be set to add a decoration for the header comment so headers look similar to the ones generated by the StyleCop Classic ReSharper fix |
 
 #### Configuring Copyright Text
 
@@ -575,3 +575,48 @@ File naming convention | Expected file name
 -----------------------| ------------------
 stylecop               | Class1{T1,T2,T3}.cs
 metadata               | Class1`3.cs
+
+## Sharing configuration among solutions
+
+It is possible to define your preferred configuration once and reuse it across multiple independent projects. This involves rolling out your own NuGet package,
+which will contain the `stylecop.json` configuration and potentially a custom ruleset file. A custom `.props` file glues that configuration to any project
+that wil use the NuGet package.
+
+Example nuspec file:
+
+```xml
+<?xml version="1.0"?>
+<package>
+  <metadata>
+    <id>acme.stylecop</id>
+    <version>1.0.0</version>
+    <dependencies>
+      <dependency id="StyleCop.Analyzers" version="1.0.2" />
+    </dependencies>
+  </metadata>
+  <files>
+    <file src="stylecop.json" target="" />
+    <file src="acme.stylecop.ruleset" target="" />
+    <file src="acme.stylecop.props" target="build" />
+  </files>
+</package>
+```
+
+Example props file:
+
+```xml
+<?xml version="1.0" encoding="utf-8"?>
+<Project ToolsVersion="14.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <PropertyGroup>
+    <CodeAnalysisRuleSetLocation Condition=" '$(NuGetPackageRoot)' != '' ">$(NuGetPackageRoot)acme.stylecop\1.0.0</CodeAnalysisRuleSetLocation>
+    <CodeAnalysisRuleSetLocation Condition=" '$(CodeAnalysisRuleSetLocation)' == '' and '$(SolutionDir)' != '' ">$(SolutionDir)packages\acme.stylecop.1.0.0</CodeAnalysisRuleSetLocation>
+    <CodeAnalysisRuleSetLocation Condition=" '$(CodeAnalysisRuleSetLocation)' == '' ">$([System.IO.Path]::GetDirectoryName($(MSBuildProjectDirectory)))\packages\acme.stylecop.1.0.0</CodeAnalysisRuleSetLocation>
+  </PropertyGroup>
+  <PropertyGroup>
+      <CodeAnalysisRuleSet>$(CodeAnalysisRuleSetLocation)\acme.stylecop.ruleset</CodeAnalysisRuleSet>
+  </PropertyGroup>
+  <ItemGroup>
+    <AdditionalFiles Include="$(CodeAnalysisRuleSetLocation)\stylecop.json" Link="stylecop.json" />
+  </ItemGroup>
+</Project>
+```