docs: add module grouping to generated docs #689

Job	Run time
ash-ci / mix igniter.upgrade	0s
ash-ci / mix deps.get	21s
ash-ci / audit	46s
ash-ci / MIX_ENV=test mix.compile	24s
ash-ci / mix credo --strict	4s
ash-ci / MIX_ENV=dev mix.compile	31s
ash-ci / mix ash.codegen --check	0s
ash-ci / mix docs	22s
ash-ci / Deploy docs to GitHub pages.	0s
ash-ci / mix dialyzer	2m 32s
ash-ci / mix format --check-formatted	18s
ash-ci / mix sobelow	6s
ash-ci / mix spark.cheat_sheets --check	6s
ash-ci / mix spark.formatter --check	6s
ash-ci / mix test	1m 20s
ash-ci / mix deps.unlock --check-unused	27s
ash-ci / Release	0s
	7m 23s

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