chore(kb): add certbot article

knowledge base/certbot.md

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+# Certbot
+
+Client that fetches a TLS certificate from [Let's Encrypt] and deploys it to a web server.
+
+1. [TL;DR](#tldr)
+1. [Further readings](#further-readings)
+   1. [Sources](#sources)
+
+## TL;DR
+
+Meant to be run on one's web server via the CLI.
+
+<details>
+  <summary>Setup</summary>
+
+```sh
+pip install 'certbot'
+pip install 'certbot-dns-cloudflare'  # leverage cloudflare
+pip install 'certbot-dns-route53'  # leverage AWS Route53
+
+# Integrate with Nginx.
+dnf install 'certbot' 'nginx' 'python3-certbot-nginx'
+```
+
+</details>
+
+<details>
+  <summary>Usage</summary>
+
+```sh
+# Request a certificate.
+docker run -it --rm --name 'certbot' \
+  -v '/etc/letsencrypt:/etc/letsencrypt' -v '/var/lib/letsencrypt:/var/lib/letsencrypt' \
+  'certbot/certbot' certonly
+
+# Request a certificate and validate it over DNS leveraging AWS Route53.
+docker run -it --rm --name 'certbot' \
+  -v "$HOME/.aws:/root.aws:ro" \
+  -v '/etc/letsencrypt:/etc/letsencrypt' -v '/var/lib/letsencrypt:/var/lib/letsencrypt' \
+  'certbot/dns-route53' certonly
+
+# Request a certificate.
+# Certbot will temporarily spin up a web server listening on port 80 on the running machine.
+certbot certonly --standalone
+
+# Request a certificate *without* temporarily spin up a web server listening on port 80 on the running machine.
+certbot certonly --webroot
+
+# Request a certificate leveraging a running Nginx server.
+certbot --nginx -d 'code.example.org' --non-interactive --agree-tos -m 'someone@example.org'
+
+# Request a certificate leveraging AWS Route53.
+certbot certonly --dns-route53 -d 'example.org' -d 'www.example.org'
+
+# Request a certificate leveraging Cloudflare.
+certbot certonly --dns-cloudflare --dns-cloudflare-credentials ~'/.secrets/certbot/cloudflare.ini' \
+  --dns-cloudflare-propagation-seconds 60 -d 'example.org'
+
+# Renew certificates.
+certbot renew -q
+```
+
+</details>
+
+<!-- Uncomment if used
+<details>
+  <summary>Real world use cases</summary>
+
+```sh
+```
+
+</details>
+-->
+
+## Further readings
+
+- [Website]
+- [Codebase]
+- [Let's Encrypt]
+- [Nginx]
+
+### Sources
+
+- [Documentation]
+
+<!--
+  Reference
+  ═╬═Time══
+  -->
+
+<!-- In-article sections -->
+<!-- Knowledge base -->
+[let's encrypt]: letsencrypt.md
+[nginx]: nginx.md
+
+<!-- Files -->
+<!-- Upstream -->
+[codebase]: https://github.com/certbot/certbot
+[documentation]: https://certbot.eff.org/docs
+[website]: https://certbot.eff.org/
+
+<!-- Others -->