manuals: Add script to regenerate vty/counter documentation

Change-Id: Iff570e85828c87d69a7a49a00d9459094077ca30
Related: OS#1700
diff --git a/doc/manuals/Makefile.am b/doc/manuals/Makefile.am
index 96675ec..a29b48f 100644
--- a/doc/manuals/Makefile.am
+++ b/doc/manuals/Makefile.am
@@ -3,6 +3,7 @@
     osmopcu-usermanual.adoc \
     osmopcu-usermanual-docinfo.xml \
     osmopcu-vty-reference.xml \
+    regen_doc.sh \
     chapters \
     gb \
     vty