Update v1.2.0 gif

Add a shorter gif

Author: vviau

releases/v1.2.0.md

@@ -5,7 +5,7 @@
   * View editors side-by-side
   * Drag the tab heading to place an Arc editor in a different location
 
-<img src="https://s3-ap-southeast-2.amazonaws.com/downloads.cubewise.com/web_assets/arc-pulgins/TabNavigation.gif" />
+<img src="https://s3-ap-southeast-2.amazonaws.com/downloads.cubewise.com/web_assets/arc-pulgins/tab-navigation-short.gif" />
 
 ## Fixes
 * Cube viewer supports now views without dimensions on rows. [#256](https://github.com/cubewise-code/arc-issues/issues/256)