Include changelog annotation message

Annotation message is meant as official release note, so including it
there makes sense.

(For example, GitHub will use it to create release note under Releases tab.)

src/include/release.sh

     set -e
     debug_var newtag
     $MKIT_DRY && return
-    git tag -m "$(ini 1value project:name) $newtag - $(ini 1value project:codename)" "$newtag"
+    git tag -m "$(_release_msg)" "$newtag"
 
     reldst=$(ini 1value project:reldst)
     debug_var reldst
     fi
 }
 
+_release_msg() {
+    #
+    # Generate message for annotated tag
+    #
+    # The last commit before issuing a release must be "Bump version" commit
+    # suggested by _vbump_gitmsg() and  manually edited by user.  Since the
+    # commit contains changelog, this function just uses the message body.
+    #
+    # The sort message (first line) is replaced with a nicer one (with project
+    # name, codename and version).
+    #
+    echo "$(ini 1value project:name) $newtag - $(ini 1value project:codename)"
+    echo
+    git show -s --format=%B \
+      | tail -n +3
+}
+
 _vbump() {
     local rlevel="$1"
     local nextver   # after the bump