Update example formatting (#57)

* adjust formatting of Carthage example

* enable syntax highlighting for Cargo example

examples.md

@@ -36,6 +36,7 @@
 
 ## 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
   with:
@@ -70,7 +71,7 @@ Using [NuGet lock files](https://docs.microsoft.com/nuget/consume-packages/packa
 ## Swift, Objective-C - Carthage
 
 ```yaml
-uses: actions/cache@v1
+- uses: actions/cache@v1
   with:
     path: Carthage
     key: ${{ runner.os }}-carthage-${{ hashFiles('**/Cartfile.resolved') }}
@@ -123,7 +124,7 @@ uses: actions/cache@v1
 
 ## Rust - Cargo
 
-```
+```yaml
 - name: Cache cargo registry
   uses: actions/cache@v1
   with: