[roll pigweed] docs: Minor additions for preprocessor macro style

- Reference the preprocessor macro usage guidelines from the macro
  naming guidelines section.
- Link the GCC docs about swallowing the semicolon in macros.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/98440

https://pigweed.googlesource.com/pigweed/pigweed
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Change-Id: I0caabc08441006a0002ebabebf5decaeffb83498
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/zephyr-integration/+/100341
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1 file changed
tree: ec5a3f217355fa295291f2762a6bdc591ca274da
  1. .gitmodules
  2. test.sh