Initialize neutral embed input for extras builds

ober

353996192639e01185cc0e38ef9143b8e05b87ba

diff --git a/Makefile b/Makefile
index e236a72..7667704 100644
--- a/Makefile
+++ b/Makefile
@@ -135,6 +135,7 @@ stage-jsqlite: ensure-jsqlite
 		-o -name '*.tarm64osx' -o -name '*.tx86_64osx' \) -delete 2>/dev/null || true
 
 extras: configure
+	@mkdir -p "$(JSH_EMBED)"
 	@echo "=== Fetching dependencies for the selected jerboa-shell extras ==="
 	@$(MAKE) vendor-deps
 	@echo "=== Building jerboa-shell with selected extras ==="
diff --git a/README.md b/README.md
index f94d915..2d60c95 100644
--- a/README.md
+++ b/README.md
@@ -13,7 +13,8 @@ make extras
 That command fetches this repository, opens an interactive feature menu, fetches
 the external Jerboa package set, and builds the enhanced shell as `jsh-extras`
 in the jerboa-shell checkout. Use Space to toggle an item, `a` for all, `n` for
-none, and Enter to save the selection and build.
+none, and Enter to save the selection and build. The target initializes an
+empty local `embed/` directory when no embed input has been supplied.
 
 The available groups are declared in `features.def` and currently cover built-in
 coreutils, mux, encrypted embed/pass/vault storage, SSH, YubiKey, AWS, wormhole,