doc(coding_style): add how to organize template source code

[skip ci]
fix(kernel/normalizer): do not apply substitutions in the normalizer

It is incorrect to apply substitutions during normalization.
The problem is that we do not have support for tracking justifications in the normalizer. So, substitutions were being silently applied during normalization. Thus, the correctness of the conflict resolution in the elaboration was being affected.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>