docs: how to run clang-format in podman

docs/CONTRIBUTING.rst

@@ -14,14 +14,22 @@ Such changes should always be made in consultation with the core development tea
 Code Formatting
 ---------------
 
-All code shall be formatted by clang-format 8:
+All code shall be formatted by clang-format 14:
 
 .. code-block:: bash
 
   shopt -s globstar
   clang-format-14 -i {src,unit_tests,perf_tests}/**/*.[ch]pp
 
 
+Alternatively, you can use docker/podman: (expects $PWD to be the kokkos-comm tree)
+
+.. code-block:: bash
+
+  shopt -s globstar
+  podman run -v $PWD:/src xianpengshen/clang-tools:14 clang-format -i {src,unit_tests,perf_tests}/**/*.[ch]pp
+
+
 Behavioral Expectations
 -----------------------