chore: only build newest changelog

Makefile

-export RELEASE_DIR_STEM := sinologie-1
+export RELEASE_DIR_STEM := sinology-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
-apkg: build
-	$(MAKE) -C build
+.PHONY: all
+all: build
+# git commands in submake use the parent repo to generate the changelog, not
+# the build repo
+	GIT_DIR=$(PWD)/.git $(MAKE) -C build apkg announce changelog-last-version
 
 .PHONY: mostlyclean
 mostlyclean:
@@ -24,4 +23,4 @@ deepclean:
 build: build.git build.sha
 	-rm -rf build
 	git clone $(file < build.git) build
-	cd build && GIT_DIR=$(PWD)/build/.git git reset --hard $(file < build.sha)
+	cd build && git reset --hard $(file < build.sha)