manuals: Add script to update vty/counter documentation from docker

Related: OS#1700
Change-Id: Id57c34214396b02fafa55da223764748086290e8
diff --git a/doc/manuals/Makefile.am b/doc/manuals/Makefile.am
index 9e1295a..8a47f8a 100644
--- a/doc/manuals/Makefile.am
+++ b/doc/manuals/Makefile.am
@@ -4,6 +4,7 @@
     osmohlr-usermanual.adoc \
     osmohlr-usermanual-docinfo.xml \
     osmohlr-vty-reference.xml \
+    regen_doc.sh \
     chapters \
     vty