Makefile: fix clean target

Signed-off-by: Nicolas Sebrecht <nicolas.s-dev@laposte.net>

Makefile

@@ -38,7 +38,7 @@ clean:
 	-find . -name '.cache*' -exec rm -f {} \;
 	-rm -f manpage.links manpage.refs 2>/dev/null
 	-find . -name auth -exec rm -vf {}/password {}/username \;
-	@$(MAKE) -C clean
+	-$(MAKE) -C docs clean
 
 .PHONY: docs
 docs:

docs/Makefile

@@ -48,6 +48,6 @@ clean:
 	$(RM) -f offlineimap.7
 	$(RM) -f manhtml/*
 	$(RM) -rf html/*
-	-find ./docs -name '*.html' -exec rm -f {} \;
+	-find . -name '*.html' -exec rm -f {} \;
 
 .PHONY: clean doc