readme: clarify need to provide external program
pww is little more than a glorified script which binds together the stages of the image identification process, outsourcing each stage to a more capable library or program. pww does the following:
1) convert the image to a format fit for analysis (if required)
-2) pass the image to a program or script for analysis
+2) pass the image to a user-provided program or script for analysis
3) normalize the textual tags generated by the analysis script
4) write the tags as metadata to the image file and/or its XMP sidecar file
Its behavior is quite configurable via a TOML configuration file, and it is suitable for calling from scripts or plugins, so it can be integrated into an image organizer like Darktable.
-Notice: do **not** trust this tool with images that have not been backed up! Permanent data loss may occur!
+Note: An analysis program is *required*, but not provided. This tool is intended for power-users to build custom workflows. See the example below for instructions to make a basic LLM categorization script.
+
+Warning: Do **not** trust this tool with images that have not been backed up! Permanent data loss may occur!
## Purpose