Small typos and missed words in MonoGame 2d game tutorial (MonoGame#182)

* Fix typo in ch 10 of the 2D game tutorial

* Corrected variable name to match class name. "Tileset" not "TileSet"

* typo: added missing space

* Changed default pitch value. Short version of PlaySoundEffect method was playing up an octave by default.

* missing word in FromFile method summary

Author: Becon032

articles/tutorials/building_2d_games/07_optimizing_texture_rendering/snippets/textureatlas.cs

@@ -88,7 +88,7 @@ public void Clear()
     }
 
     /// <summary>
-    /// Creates a new texture atlas based a texture atlas xml configuration file.
+    /// Creates a new texture atlas based on a texture atlas xml configuration file.
     /// </summary>
     /// <param name="content">The content manager used to load the texture for the atlas.</param>
     /// <param name="fileName">The path to the xml file, relative to the content root directory.</param>

articles/tutorials/building_2d_games/13_working_with_tilemaps/snippets/tilemap.cs

@@ -126,8 +126,8 @@ public void Draw(SpriteBatch spriteBatch)
     {
         for (int i = 0; i < Count; i++)
         {
-            int tileSetIndex = _tiles[i];
-            TextureRegion tile = _tileset.GetTile(tileSetIndex);
+            int tilesetIndex = _tiles[i];
+            TextureRegion tile = _tileset.GetTile(tilesetIndex);
 
             int x = i % Columns;
             int y = i / Columns;

articles/tutorials/building_2d_games/15_audio_controller/snippets/audiocontroller.cs

@@ -88,7 +88,7 @@ public float SoundEffectVolume
     /// <summary>
     /// Gets a value that indicates if this audio controller has been disposed.
     /// </summary>
-    public bool IsDisposed {get; private set; }
+    public bool IsDisposed { get; private set; }
     #endregion
 
     #region ctors
@@ -168,7 +168,7 @@ protected void Dispose(bool disposing)
     /// <returns>The sound effect instance created by this method.</returns>
     public SoundEffectInstance PlaySoundEffect(SoundEffect soundEffect)
     {
-        return PlaySoundEffect(soundEffect, 1.0f, 1.0f, 0.0f, false);
+        return PlaySoundEffect(soundEffect, 1.0f, 0.0f, 0.0f, false);
     }
 
     /// <summary>