Document module-aware menuet.mk include path

README.md

@@ -59,9 +59,12 @@ app directory, create a `Makefile` like:
 ```make
 APP=My App
 IDENTIFIER=com.example.myapp
-include $(GOPATH)/src/github.com/caseymrm/menuet/menuet.mk
+include $(shell go list -m -f '{{.Dir}}' github.com/caseymrm/menuet)/menuet.mk
 ```
 
+(`go list -m` locates menuet in the module cache; the old
+`$(GOPATH)/src/...` path only works for pre-modules GOPATH checkouts.)
+
 Then `make run` builds the binary into `My App.app/Contents/MacOS/myapp`,
 generates `My App.app/Contents/Info.plist` with your `CFBundleIdentifier`,
 and launches it. The `cmd/catalog` example uses this pattern.

menuet.mk

@@ -3,7 +3,10 @@
 # For example:
 #
 #   APP=Hello World
-#   include $(GOPATH)/src/github.com/caseymrm/menuet/menuet.mk
+#   include $(shell go list -m -f '{{.Dir}}' github.com/caseymrm/menuet)/menuet.mk
+#
+# (go list -m finds menuet in the module cache; use a direct path instead
+# if you have a local checkout.)
 #
 # Optional features:
 #