readme: mention darktable lua plugin
You should **absolutely not use this tool on photos that have not been backed up**! It is mostly **untested** and entirely **unwarranted** and **unguaranteed** and it **should not be trusted**.
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+## Darktable Plugin
+
+A minimal Lua plugin for Darktable is included, `darktable/photo-what-what.lua`.
+
+The plugin adds a single "auto-tag images (pww)" button to the "Action on Selection" menu in the Lightroom view. Select one or more images, click auto-tag, and the process of tagging runs in the background.
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+If necessary, paths to pww itself and the desired identifier binary/script can be configured in Darkroom's settings under the "Lua options" tab. This is unnecessary if the `photo-what-what` binary is in your path and the identifier binary is specified in your `pww_config.toml`.
+
+Install it via Darktable's extremely user-unfriendly standard method: copy it to `~/.config/darktable/lua/contrib/photo-what-what.lua`, manually append `require "contrib/photo-what-what"` to `~/.config/darktable/luarc`, and restart Darktable. (Paths may be different, depending on OS and configuration.)
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+
## Related solutions
At the time this was written (early 2025), I could not find any free solutions for local automatic content tagging with AI/ML/DL/LLMs in Linux that were compatible with my photo workflow.