T.: Document manual user registration

docs/register-user.md

@@ -0,0 +1,28 @@
+# Registering users manually
+You might want to disable registration in your [instance config](/configuration), but still have a quick way to manually register users upon request. To do so, first set up a separate instance that only listens on localhost, has registration enabled,
+and captchas as well as background jobs disabled. Make sure you have a way to start it easily with just one or a few commands, e.g. via a systemd service. Then, use something like the script below (in the example, the instance is started via a systemd
+service called `podman-invidious_register`, and it listens on localhost port 21742. **Warning**: This script is vulnerable to SQL injections. Only use trusted inputs; if you want to make a custom signup form and use this as a backend, be sure to
+sanitize inputs.
+```sh
+#!/usr/bin/env bash
+set -e
+
+systemctl start podman-invidious_register
+
+CONTINUE='y'
+while [ "$CONTINUE" = 'y' ]; do
+    read -rp 'User ID: ' ID
+    if [ "$(su postgres -c "psql invidious -c \"SELECT email FROM users WHERE email = '$ID';\"" | tail -n 2 | head -n 1)" != '(0 rows)' ]; then
+        echo 'Error: User ID is already taken'
+        continue
+    fi
+
+    read -rsp 'Password: ' PASSWORD
+
+    curl -L 'http://localhost:21742/login' --form-string "email=$ID" --form-string "password=$PASSWORD" -F 'action=signin' >/dev/null
+
+    read -rp 'Register more accounts? [y/N] ' CONTINUE
+done
+
+systemctl stop podman-invidious_register
+```

mkdocs.yml

@@ -33,6 +33,7 @@ nav:
     - 'ipv6-rotator.md'
     - 'captcha-bug.md'
     - 'anti-captcha.md'
+    - 'register-user.md'
     - 'reset-password.md'
     - 'known-exception.md'
   - 'For Developers':