document feedback script in README

README.md

@@ -81,4 +81,17 @@ usage: `python clone_forks_from_json.sh forks.json clone_dir`
 
 After grading student assignment, the teacher may want to send student groups their grades, as well as positive or critical comments on their solution. This can be automated as well, using the Gitlab issues API. We provide a script to read a csv file containing grades and comments for each student group and open issues in the corresponding repositories automatically.
 
-> TODO
+script: [teach_utils/send_feedback.py](teach_utils/send_feedback.py)
+
+usage: `python ./send_feedback.py forks.json grades.csv`
+
+By default, this script will read grades and comments from `grades.csv` and open an issue for each repository in forks.json. The issue description uses a default template with grades and comments inserted in it. Forks can also be read from stdin, and users can specify a default template. One could also use this script to warn all groups that their fork is public for example:
+
+```
+echo ":warning: Your fork is public, please make it private!" > visibility.md
+
+./collect_forks https://renkulab.io/gitlab/class/homework \
+  | jq '.[] | select(.visibility == "public")' \
+  ./send_feedback.py --template visibility.md grades.csv
+
+```