docs(examples): add image reference example note with all three scenarios

Adds notes/example-images.org demonstrating how org-mode image links of
each kind pass through ox-hugo and land in content/:

  Scenario 1 — External URL: linked image using #+ATTR_HTML + a local
    thumbnail as the display image; ox-hugo emits a {{< figure >}} shortcode
    with a link= attribute pointing to the remote URL.

  Scenario 2 — Local file (same notes dir): [[file:quartz-logo.jpg]]
    ox-hugo copies the file to static/ox-hugo/ and rewrites the src to
    /ox-hugo/quartz-logo.jpg.

  Scenario 3 — Absolute path outside notes dir: [[file:/abs/path/img.jpg]]
    ox-hugo copies the file from outside the notes tree into static/ox-hugo/
    and rewrites the src identically to scenario 2.

Also adds:
  notes/quartz-logo.jpg          — image asset for scenarios 1 & 2
  notes-external/                — simulates an assets dir outside notes
  static/ox-hugo/ added to .gitignore (populated at export time)

notes/example-images.org

@@ -0,0 +1,33 @@
+:PROPERTIES:
+:ID:       example-images
+:END:
+#+title: Example: Image References
+
+This note demonstrates the three image reference scenarios that the pipeline
+must handle.
+
+* Scenario 1: External image (URL)
+
+An image hosted on the web — ox-hugo passes the URL through as-is and no
+local file handling is needed.
+
+#+ATTR_HTML: :alt Quartz logo (external URL)
+[[https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcSkzsTuLOt8esM6enoKwkzqA52G3p9hldlf2g&s][file:quartz-logo.jpg]]
+
+* Scenario 2: Local image (same notes directory)
+
+An image sitting next to this .org file inside the notes directory.
+ox-hugo copies files referenced with a relative path into the Hugo =static/=
+assets tree automatically.
+
+#+CAPTION: Quartz logo (local, same notes dir)
+[[file:quartz-logo.jpg]]
+
+* Scenario 3: External image (outside notes directory)
+
+An image that lives outside the notes directory entirely — for example a
+shared assets folder or a system path. ox-hugo still copies it into =static/=
+and rewrites the reference.
+
+#+CAPTION: Quartz logo (outside notes dir)
+[[file:/home/ignaciobll/code/quartz-org-roam/notes-external/external-location-image.jpg]]