docs: Document gcc and clang toolchains

Document gcc and clang as supported toolchains, and how to switch between them

Signed-off-by: Bernhard Rosenkränzer bernhard.rosenkraenzer.ext@huawei.com

docs/index.rst

@@ -37,6 +37,12 @@ Build System Guide
    supported-technologies/openthread
    supported-technologies/containers
 
+.. toctree::
+   :caption: Supported Toolchains
+   :maxdepth: 2
+
+   toolchains
+
 .. toctree::
    :caption: Troubleshoot
    :maxdepth: 2