Add openssf scorecard link to README (#67)

Signed-off-by: Marikkannu, Suresh <[email protected]>

Author: sureshmarikkannu

README

@@ -3,6 +3,8 @@
    SPDX-FileCopyrightText: 2021 Open Networking Foundation <[email protected]>
    SPDX-License-Identifier: Apache-2.0
 
+[![OpenSSF Scorecard](https://api.scorecard.dev/projects/github.com/omec-project/sdcore-docs/badge)](https://scorecard.dev/viewer/?uri=github.com/omec-project/sdcore-docs)
+
 SD-Core Docs
 ==============