Replace personal data with variables and placeholders

- Replace hardcoded password in code-server config with ${CODE_SERVER_PASSWORD}
- Replace domain kelin-hass.duckdns.org with yourdomain.duckdns.org in docs
- Replace domain kelinreij.duckdns.org with yourdomain.duckdns.org in homepage config
- Replace personal emails with example addresses
- Replace DuckDNS token and credentials in markup.yml with placeholders
- Replace Let's Encrypt account numbers with placeholders

Co-authored-by: kelinfoxy <67766943+kelinfoxy@users.noreply.github.com>

docker-compose/infrastructure/code-server/config/.config/code-server/config.yaml

@@ -1,4 +1,4 @@
 bind-addr: 127.0.0.1:8080
 auth: password
-password: 4d6c2b20e8d2c62be2512281
+password: ${CODE_SERVER_PASSWORD}
 cert: false