add a release guide

Even though there are very few steps involved, it is good to have it documented.

.gitlab-ci.yml

@@ -11,6 +11,11 @@ test:
 
 authors check:
   script:
+    - GITLOG=`echo $(git shortlog -s)`
+    - echo $GITLOG
+    - echo "$(git shortlog -s)"
+    - AUTHORS=$(git --no-pager shortlog -nse HEAD | cut -f 2-)
+    - echo $AUTHORS
     - AUTHORS=$(git shortlog -s | sed -e "s/^[0-9\t ]*//"| xargs -i sh -c 'grep -q "{}" AUTHORS.md || echo "{} missing from authors"')
     - echo $AUTHORS
     - if [ ! -z $AUTHORS ]; then { echo $AUTHORS; exit 1; }; fi