github: workflows: Add Scorecards badge

Add the OpenSSF Scorecards badge to README.rst

Signed-off-by: Pedro Kaj Kjellerup Nacht <pedro.k.night@gmail.com>

README.rst

@@ -10,12 +10,15 @@
      </p>
    </a>
 
-   <a href="https://bestpractices.coreinfrastructure.org/projects/74"><img
-   src="https://bestpractices.coreinfrastructure.org/projects/74/badge"></a>
-   <a
-   href="https://github.com/zephyrproject-rtos/zephyr/actions/workflows/twister.yaml?query=branch%3Amain">
-   <img
-   src="https://github.com/zephyrproject-rtos/zephyr/actions/workflows/twister.yaml/badge.svg?event=push"></a>
+   <a href="https://bestpractices.coreinfrastructure.org/projects/74">
+     <img src="https://bestpractices.coreinfrastructure.org/projects/74/badge">
+   </a>
+   <a href="https://scorecard.dev/viewer/?uri=github.com/zephyrproject-rtos/zephyr">
+     <img src="https://api.securityscorecards.dev/projects/github.com/zephyrproject-rtos/zephyr/badge">
+   </a>
+   <a href="https://github.com/zephyrproject-rtos/zephyr/actions/workflows/twister.yaml?query=branch%3Amain">
+     <img src="https://github.com/zephyrproject-rtos/zephyr/actions/workflows/twister.yaml/badge.svg?event=push">
+   </a>
 
 
 The Zephyr Project is a scalable real-time operating system (RTOS) supporting