[build]: add barefoot master build badge (#1881)

Author: lguohan

README.md

@@ -1,4 +1,6 @@
-*master*: Broadcom: [![Broadcom](https://sonic-jenkins.westus2.cloudapp.azure.com/job/broadcom/job/buildimage-brcm-all/badge/icon)](https://sonic-jenkins.westus2.cloudapp.azure.com/job/broadcom/job/buildimage-brcm-all)
+*master*:
+Barefoot: [![Barefoot](https://sonic-jenkins.westus2.cloudapp.azure.com/job/barefoot/job/buildimage-bf-all/badge/icon)](https://sonic-jenkins.westus2.cloudapp.azure.com/job/barefoot/job/buildimage-bf-all)
+Broadcom: [![Broadcom](https://sonic-jenkins.westus2.cloudapp.azure.com/job/broadcom/job/buildimage-brcm-all/badge/icon)](https://sonic-jenkins.westus2.cloudapp.azure.com/job/broadcom/job/buildimage-brcm-all)
 Mellanox: [![Mellanox](https://sonic-jenkins.westus2.cloudapp.azure.com/job/mellanox/job/buildimage-mlnx-all/badge/icon)](https://sonic-jenkins.westus2.cloudapp.azure.com/job/mellanox/job/buildimage-mlnx-all)
 Nephos: [![Nephos](https://sonic-jenkins.westus2.cloudapp.azure.com/job/nephos/job/buildimage-nephos-all/badge/icon)](https://sonic-jenkins.westus2.cloudapp.azure.com/job/nephos/job/buildimage-nephos-all)
 P4: [![P4](https://sonic-jenkins.westus2.cloudapp.azure.com/job/p4/job/buildimage-p4-all/badge/icon)](https://sonic-jenkins.westus2.cloudapp.azure.com/job/p4/job/buildimage-p4-all)