docs caching change Piranha.Caching to Piranha.Cache

The Piranha.Caching.CacheLevel is actually in Piranha.Cache
at least in 10.x versions...

src/04. Architecture/03. Caching/Index.md

@@ -30,15 +30,15 @@ By default Piranha caches **everything** when a Cache Service is registered, but
 ##### CacheLevel.None
 
 ~~~ csharp
-Piranha.App.CacheLevel = Piranha.Caching.CacheLevel.None;
+Piranha.App.CacheLevel = Piranha.Cache.CacheLevel.None;
 ~~~
 
 Nothing is cached even if a cache service is registered.
 
 ##### CacheLevel.Minimal
 
 ~~~ csharp
-Piranha.App.CacheLevel = Piranha.Caching.CacheLevel.Minimal;
+Piranha.App.CacheLevel = Piranha.Cache.CacheLevel.Minimal;
 ~~~
 
 The following data is kept in cache:
@@ -49,7 +49,7 @@ The following data is kept in cache:
 ##### CacheLevel.Basic
 
 ~~~ csharp
-Piranha.App.CacheLevel = Piranha.Caching.CacheLevel.Basic;
+Piranha.App.CacheLevel = Piranha.Cache.CacheLevel.Basic;
 ~~~
 
 The following data is kept in cache:
@@ -62,7 +62,7 @@ The following data is kept in cache:
 ##### CacheLevel.Full
 
 ~~~ csharp
-Piranha.App.CacheLevel = Piranha.Caching.CacheLevel.Full;
+Piranha.App.CacheLevel = Piranha.Cache.CacheLevel.Full;
 ~~~
 
-Everything is kept in cache, including all Blocks and Fields for Content Types. This is the default cache level.
+Everything is kept in cache, including all Blocks and Fields for Content Types. This is the default cache level.