Catch-up with git version tags

* update debian/changelog
* update TODO-RELEASE
* add comments to Makefile.am and TODO-RELEASE to simplify the process
  in future
* add link to libtool docs to Makefile.am to simplify LIBVERSION
  maintenance

Related: OS#1861
Change-Id: I22c257e357f597519120232d742d6a61289db021
diff --git a/src/gsm/Makefile.am b/src/gsm/Makefile.am
index 4ea55e1..4ec441f 100644
--- a/src/gsm/Makefile.am
+++ b/src/gsm/Makefile.am
@@ -1,6 +1,7 @@
 # This is _NOT_ the library release version, it's an API version.
-# Please read Chapter 6 "Library interface versions" of the libtool documentation before making any modification
-LIBVERSION=6:0:1
+# Please read chapter "Library interface versions" of the libtool documentation
+# before making any modifications: https://www.gnu.org/software/libtool/manual/html_node/Versioning.html
+LIBVERSION=7:0:1
 
 AM_CPPFLAGS = -I$(top_srcdir)/include -I$(top_builddir)/include $(TALLOC_CFLAGS)
 AM_CFLAGS = -Wall ${GCC_FVISIBILITY_HIDDEN}