rewrite jxl-restore -> jxl-convert

Signed-off-by: Martin Matous <m@matous.dev>

README.md

@@ -90,17 +90,14 @@ Dependencies: openssl
 Usage: ???
 
 
-## jxl-restore.py
-Check whether JPEG version of .jxl exists, remove .jxl if does.
-Attempt at rescuing collection where conversion got messed up.
+## jxl-convert.py
+Recursively convert jpgs to jxls with additional checks.
 
-Will fix one day. Maybe.
+Status: one-off
 
-Status: ancient one-off, broken
+Dependencies: libjxl
 
-Dependencies: None
-
-Usage: None
+Usage: `./jxl-convert.py /path/to/pics`
 
 
 ## invoke-magic.bat