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

Change-Id: I3f5573f81460b40d4606fbcf0febcfd078a7bdca
Related: OS#1700
diff --git a/doc/manuals/Makefile.am b/doc/manuals/Makefile.am
index 2ce6a0a..3b50d4e 100644
--- a/doc/manuals/Makefile.am
+++ b/doc/manuals/Makefile.am
@@ -1,6 +1,7 @@
 EXTRA_DIST = osmomsc-usermanual.adoc \
     osmomsc-usermanual-docinfo.xml \
     osmomsc-vty-reference.xml \
+    regen_doc.sh \
     chapters \
     images \
     vty