diff --git a/.markdownlintrc b/.markdownlintrc
index 2ae23a97172715cf4eaa9d43924b84abbe5bf12e..ea7570088d5c4555997b26c5a3f29ddb300ca080 100644
--- a/.markdownlintrc
+++ b/.markdownlintrc
@@ -1,5 +1,6 @@
 {
   "default": true,
+  "frontmatter": true,
   "MD013": {
     "line_length": 120,
     "code_block_line_length": 140,
diff --git a/docs/container/security.md b/docs/container/security.md
index f79a9d573bce964474bb9bac87951095fc05f492..aadd4c50a644367cb7e325cd2172a77b4ff75e33 100644
--- a/docs/container/security.md
+++ b/docs/container/security.md
@@ -14,12 +14,19 @@ Bundle) together with download times:
 trivy --version
 ```
 
-Scan local filesystem (i.e. to check a `Containerfile`):
+Scan local filesystem (i.e. to check a `Containerfile`, next to others):
 
 ```sh
 trivy config .
 ```
 
+Scan container image:
+
+```sh
+trivy image php:8.4.4-apache-bullseye
+trivy image php:8.4.4-apache-bullseye | head -5  # Hide details
+```
+
 ### Ignore checks
 
 [Docs: Filtering](https://aquasecurity.github.io/trivy/v0.56/docs/configuration/filtering/)
diff --git a/docs/etc/presentations/demo-slide.md b/docs/etc/presentations/demo-slide.md
new file mode 100644
index 0000000000000000000000000000000000000000..dfe21ad2b57dee8fee45e60ccef4d731103e1847
--- /dev/null
+++ b/docs/etc/presentations/demo-slide.md
@@ -0,0 +1,48 @@
+<!-- markdownlint-disable MD033 MD041 MD045 -->
+
+# Markdown demo slide
+
+- Showcase about special use cases
+
+---
+
+## Image positioning
+
+[How can one display images side by side in a GitHub README.md?](https://stackoverflow.com/q/24319505)
+
+---
+
+## Images side by side with markdown syntax
+
+![Gitlab](https://gitlab.com/uploads/-/system/group/avatar/6543/logo-extra-whitespace.png?width=96) ![Opentofu](https://www.bigdatawire.com/wp-content/uploads/2024/01/opentofu-logo.png)
+
+## Images side by side with HTML syntax
+
+<img src="https://gitlab.com/uploads/-/system/group/avatar/6543/logo-extra-whitespace.png?width=96" /> <img src="https://www.bigdatawire.com/wp-content/uploads/2024/01/opentofu-logo.png" /> <!-- markdownlint-disable-line MD013 -->
+
+### Images in tables
+
+|                                                                                                     |                                                                                       |
+| --------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------- |
+| ![Gitlab](https://gitlab.com/uploads/-/system/group/avatar/6543/logo-extra-whitespace.png?width=96) | ![Opentofu](https://www.bigdatawire.com/wp-content/uploads/2024/01/opentofu-logo.png) |
+
+- Downside: Displays a visible table with Headers around the images
+
+---
+
+### Images in floating HTML
+
+<p float="left">
+  <img src="https://gitlab.com/uploads/-/system/group/avatar/6543/logo-extra-whitespace.png?width=96" />
+  <img src="https://www.bigdatawire.com/wp-content/uploads/2024/01/opentofu-logo.png" />
+</p>
+
+---
+
+### Images in div container
+
+<div class="mx-auto mt-3">
+<img src="https://gitlab.com/uploads/-/system/group/avatar/6543/logo-extra-whitespace.png?width=96" class="float-left mr-5" width="20%"> <!-- markdownlint-disable-line MD013 -->
+
+<img src="https://www.bigdatawire.com/wp-content/uploads/2024/01/opentofu-logo.png" class="" width="20%">
+</div>
diff --git a/docs/markup/markdown/markdown.md b/docs/markup/markdown/markdown.md
index 35c71b76a9d6adce9ab5254d3d328d9477e412d1..197d0555df1eff408637abbf8f346cf00154ad56 100644
--- a/docs/markup/markdown/markdown.md
+++ b/docs/markup/markdown/markdown.md
@@ -1,9 +1,33 @@
 # Markdown
 
 - [Google Markdown style guide](https://google.github.io/styleguide/docguide/style.html)
+
+## Markdown syntax
+
 - [Markdownguide](https://www.markdownguide.org)
   - [Tools](https://www.markdownguide.org/tools)
   - [Extended syntax](https://www.markdownguide.org/extended-syntax/#overview)
+- [Github Flavored Markdown](https://docs.github.com/en/get-started/writing-on-github/getting-started-with-writing-and-formatting-on-github/basic-writing-and-formatting-syntax)
+
+### Images
+
+Basic usage (no scaling options):
+
+```markdown
+![Opentofu](./assets/opentofu.png)
+```
+
+Use html:
+
+```html
+<img src="./assets/gitlab.png" width="300" height="200" />
+```
+
+#### Image positioning
+
+[How can one display images side by side in a GitHub README.md?](https://stackoverflow.com/q/24319505)
+
+see [presentations/demo-slide.md](../../etc/presentations/demo-slide.md)
 
 ## Prettyfi markdown
 
diff --git a/lychee.toml b/lychee.toml
index cea0944e3e8427642d6b8b758d0b5a44172f083f..6e6db15112935f6057e6265894dec9e04677cf9b 100644
--- a/lychee.toml
+++ b/lychee.toml
@@ -8,8 +8,7 @@
 
 exclude = [
   '^https://www\.raspberrypi\.com/.*',
-  '^https://demo\.hedgedoc\.org/slide-example.*',
-  '^https://demo\.hedgedoc\.org/features.*',
+  '^https://demo\.hedgedoc\.org.*',
 ]
 
 exclude_path = ['lychee.toml']