chore: add custom release dir stem and fix git reset

Makefile

+export RELEASE_DIR_STEM := sinologie-1
+export VERSION := $(file < version.txt)
 export CONTENT_DIR := $(PWD)/content
+# overrides the target of all git commands in this make and the the submake,
+# with the effect that changelogs are about the parent repo
 export GIT_DIR := $(PWD)/.git
 
 .PHONY: apkg
@@ -14,10 +18,10 @@ clean:
 	test -d build && $(MAKE) -C build clean || true
 
 .PHONY: deepclean
-deepclean: clean
+deepclean:
 	rm -rf build
 
 build: build.git build.sha
 	-rm -rf build
 	git clone $(file < build.git) build
-	cd build && git reset --hard $(file < build.sha)
+	cd build && GIT_DIR=$(PWD)/build/.git git reset --hard $(file < build.sha)

build.sha

-2545166f5b28ef1cec879639d4a40e3aca1e614f
+af48aa155e789bece5c5d87cbf269fc9233f09dc

version.txt

+1.0.0