docs: linter & packagers guide & chores (#64)

add prettier, move most markdown into `docs/` and add a packagers guide

---

* lint(md): add prettier

* docs(packagers): add a guide

* docs(correctness): Index -> ToC

* docs: link to package maintainers guide

* docs: move install docs to `./docs`

* docs(fix): typo

Makefile

@@ -133,6 +133,7 @@ install-service-s6-etc:
 
 pre-commit:
 	codespell
+	prettier --write "**/*.md"
 	find . -type f -name '*.sh' -not -path './assets/pkg/aur/*/src/*' | xargs shellcheck
 	clang-format -i $$(git ls-files "*.c" "*.h")
 	clang-tidy -p . $$(git ls-files "*.c" "*.h")