Fix a minor typo (#3129)

UnitySDK/Assets/ML-Agents/Scripts/DemonstrationStore.cs

     {
         public const int MetaDataBytes = 32; // Number of bytes allocated to metadata in demo file.
         readonly IFileSystem m_FileSystem;
-        const string k_DemoDirecory = "Assets/Demonstrations/";
+        const string k_DemoDirectory = "Assets/Demonstrations/";
         const string k_ExtensionType = ".demo";
 
         string m_FilePath;
         /// </summary>
         void CreateDirectory()
         {
-            if (!m_FileSystem.Directory.Exists(k_DemoDirecory))
+            if (!m_FileSystem.Directory.Exists(k_DemoDirectory))
-                m_FileSystem.Directory.CreateDirectory(k_DemoDirecory);
+                m_FileSystem.Directory.CreateDirectory(k_DemoDirectory);
             }
         }
 
         {
             // Creates demonstration file.
             var literalName = demonstrationName;
-            m_FilePath = k_DemoDirecory + literalName + k_ExtensionType;
+            m_FilePath = k_DemoDirectory + literalName + k_ExtensionType;
-                m_FilePath = k_DemoDirecory + literalName + k_ExtensionType;
+                m_FilePath = k_DemoDirectory + literalName + k_ExtensionType;
                 uniqueNameCounter++;
             }