bpo-37925: Mention --embed in python-config usage (GH-15458)

diff --git a/Misc/python-config.sh.in b/Misc/python-config.sh.in
index 59101d5..2602fe2 100644
--- a/Misc/python-config.sh.in
+++ b/Misc/python-config.sh.in
@@ -4,7 +4,7 @@
 
 exit_with_usage ()
 {
-    echo "Usage: $0 --prefix|--exec-prefix|--includes|--libs|--cflags|--ldflags|--extension-suffix|--help|--abiflags|--configdir"
+    echo "Usage: $0 --prefix|--exec-prefix|--includes|--libs|--cflags|--ldflags|--extension-suffix|--help|--abiflags|--configdir|--embed"
     exit $1
 }