Adding the Compiler Annotation guide to work-in-progress

Signed-off-by: Georg Kunz <[email protected]>

Author: gkunz

docs/index.md

@@ -38,6 +38,7 @@ guidance about memory safety through our memory safety SIG, and so on.
 Examples of ongoing work include:
 
 * [Secure Coding One Stop Shop for Python](Secure-Coding-Guide-for-Python/readme.md)
+* [Compiler Annotations for C and C++](Compiler-Hardening-Guides/Compiler-Annotations-for-C-and-C++.md)
 
 We typically use the [Simplest Possible Process (SPP)](https://best.openssf.org/spp/Simplest-Possible-Process) to publish our results on the web.