Update README.md (#35)

diff --git a/README.md b/README.md
index 8704d35..7fb3835 100644
--- a/README.md
+++ b/README.md
@@ -24,6 +24,12 @@
 git submodule update --init --recursive --progress
 ```
 
+To always get updated submodules through `git pull`, set the following flag:
+
+```shell
+git config --global submodule.recurse true
+```
+
 All following commands assume you remain in the `mpact-compiler` directory.
 
 ### Setup Python virtual environment