add a release guide

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

.gitlab-ci.yml

@@ -11,8 +11,9 @@ test:
 
 authors check:
   script:
-    - AUTHORS=`bash -c "git shortlog -s | sed -e 's/^[0-9\t ]*//'| xargs -i sh -c 'grep -q \"{}\" AUTHORS.md || echo \"{} missing from authors\"'"`
+    - GITLOG=`echo $(git shortlog -s)`
+    - echo $GITLOG
+    - AUTHORS=$(git shortlog -s | sed -e "s/^[0-9\t ]*//"| xargs -i sh -c 'grep -q "{}" AUTHORS.md || echo "{} missing from authors"')
     - echo $AUTHORS
-    # - sleep 10000
-    # - if [ ! -z $AUTHORS ]; then { echo $AUTHORS; exit 1; }; fi
+    - if [ ! -z $AUTHORS ]; then { echo $AUTHORS; exit 1; }; fi
   allow_failure: true