Update README.md

Author: jackdevey

README.md

@@ -22,8 +22,8 @@ dependencies {
 ```xml
 <me.jackdevey.codeview.CodeView
     android:id="@+id/code_view"
-    android:layout_width="wrap_content"
-    android:layout_height="wrap_content"/>
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"/>
 ```
 
 **Step 4.** Customise the CodeView