docs: Fix README to show Travis master br status

Better to show status only for master branch Travis builds.  Other branches frequently fail and cause the badge to not reflect the status of the master branch.

diff --git a/README.md b/README.md
index e18d919..bb2769d 100644 (file)
--- a/README.md
+++ b/README.md
@@ -5,7 +5,7 @@ This project provides Khronos official ICD loader and validation layers for Vulk
 ## CI Build Status
 | Platform | Build Status |
 |:--------:|:------------:|
-| Linux/Android | [![Build Status](https://travis-ci.org/KhronosGroup/Vulkan-LoaderAndValidationLayers.svg)](https://travis-ci.org/KhronosGroup/Vulkan-LoaderAndValidationLayers) |
+| Linux/Android | [![Build Status](https://travis-ci.org/KhronosGroup/Vulkan-LoaderAndValidationLayers.svg?branch=master)](https://travis-ci.org/KhronosGroup/Vulkan-LoaderAndValidationLayers) |
 | Windows |[![Build status](https://ci.appveyor.com/api/projects/status/ri4584d6qramrjiv/branch/master?svg=true)](https://ci.appveyor.com/project/Khronoswebmaster/vulkan-loaderandvalidationlayers/branch/master) |