Use Personal Cache Folder in C# Example

Ref: #115

examples.md

@@ -1,6 +1,6 @@
 # Examples
 
-- [C# - Nuget](#c---nuget)
+- [C# - NuGet](#c---nuget)
 - [Elixir - Mix](#elixir---mix)
 - [Go - Modules](#go---modules)
 - [Java - Gradle](#java---gradle)
@@ -14,13 +14,18 @@
 - [Swift, Objective-C - Carthage](#swift-objective-c---carthage)
 - [Swift, Objective-C - CocoaPods](#swift-objective-c---cocoapods)
 
-## C# - Nuget
+## C# - NuGet
 Using [NuGet lock files](https://docs.microsoft.com/nuget/consume-packages/package-references-in-project-files#locking-dependencies):
 
 ```yaml
-- uses: actions/cache@v1
+env:
+  # Use personal cache folder because global cache may have huge packages like Xamarin.
+  # Learn more, see issue #115.
+  NUGET_PACKAGES: ${{ github.workspace }}/.nuget/packages
+steps:
+  - uses: actions/cache@v1
     with:
-    path: ~/.nuget/packages
+      path: ${{ github.workspace }}/.nuget/packages
       key: ${{ runner.os }}-nuget-${{ hashFiles('**/packages.lock.json') }}
       restore-keys: |
         ${{ runner.os }}-nuget-