Change 6GB DRAM expansion to 8GB (#7313)

* Change 6GB DRAM expansion to 8GB

* Update texts and tooltips

src/Ryujinx.UI.Common/Configuration/ConfigurationFileFormat.cs

@@ -238,7 +238,7 @@ namespace Ryujinx.UI.Common.Configuration
         public MemoryManagerMode MemoryManagerMode { get; set; }
 
         /// <summary>
-        /// Expands the RAM amount on the emulated system from 4GiB to 6GiB
+        /// Expands the RAM amount on the emulated system from 4GiB to 8GiB
         /// </summary>
         public bool ExpandRam { get; set; }