diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000000000000000000000000000000000000..64c56c11366c348fbc5779f9d53c5daf73ae5fb9
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "userguide/userguide/src/mkpdfs-mkdocs-plugin"]
+	path = userguide/userguide/src/mkpdfs-mkdocs-plugin
+	url = https://github.com/jwaschkau/mkpdfs-mkdocs-plugin.git
diff --git a/userguide/src/mkpdfs-mkdocs-plugin b/userguide/src/mkpdfs-mkdocs-plugin
new file mode 160000
index 0000000000000000000000000000000000000000..655bea6fd66933876e5b93bca63f430935aa6b5b
--- /dev/null
+++ b/userguide/src/mkpdfs-mkdocs-plugin
@@ -0,0 +1 @@
+Subproject commit 655bea6fd66933876e5b93bca63f430935aa6b5b
diff --git a/userguide/src/package-lock.json b/userguide/src/package-lock.json
new file mode 100644
index 0000000000000000000000000000000000000000..48e341a0954d5f8c2accf3a6731be28e5bb9c0de
--- /dev/null
+++ b/userguide/src/package-lock.json
@@ -0,0 +1,3 @@
+{
+  "lockfileVersion": 1
+}
diff --git a/userguide/userguide/src/mkpdfs-mkdocs-plugin b/userguide/userguide/src/mkpdfs-mkdocs-plugin
new file mode 160000
index 0000000000000000000000000000000000000000..655bea6fd66933876e5b93bca63f430935aa6b5b
--- /dev/null
+++ b/userguide/userguide/src/mkpdfs-mkdocs-plugin
@@ -0,0 +1 @@
+Subproject commit 655bea6fd66933876e5b93bca63f430935aa6b5b