Write a proper README

Describes the site, its content, and the repo structure instead of
the previous one-line placeholder.

README.md

@@ -1,3 +1,16 @@
 # haemka.de
 
-Source for haemka.de
+Source for [haemka.de](https://haemka.de), a personal website. Content is a mix of technical write-ups (Linux, homelab, medical informatics, FHIR/HL7) and notes from day-to-day work and tinkering, published in both English and German.
+
+The site is built with [Pelican](https://getpelican.com/), a static site generator written in Python, using a custom theme kept in a separate repository ([pelican-latex](https://git.haemka.in/hmk/pelican-latex)) that mimics the typographic look of LaTeX documents.
+
+## Structure
+
+- `content/en/`, `content/de/` — articles, one tree per language
+- `content/pages/` — static pages such as the about page
+- `content/images/` — images referenced from articles and pages
+- `pelicanconf.py` — base site configuration
+- `publishconf.py` — production-specific overrides (imported on top of the base config)
+- `themes/latex/` — the theme, included as a git submodule
+
+Localization is handled by Pelican's `i18n_subsites` plugin: English is the default language, German is generated as a subsite of it.