📝 README.md: Rephrase/correct OCR-D usage info

See #32: "respects" is probably an ambiguous or even incorrect term. Also rephrase "it's a good idea" to "it's OK to do".

README.md

@@ -22,8 +22,8 @@ ocrd-sbb-textline-detector -I OCR-D-IMG-BIN -O OCR-D-SEG-LINE-SBB \
         -p '{ "model": "/path/to/the/models/textline_detection" }'
 ~~~
 
-Segmentation works on raw RGB images, but respects and retains
+Segmentation works on raw RGB images, but retains
-`AlternativeImage`s from binarization steps, so it's a good idea to do
+`AlternativeImage`s from binarization steps, so it's OK to do
 binarization first, then perform the textline detection. The used binarization
 processor must produce an `AlternativeImage` for the binarized image, not
 replace the original raw RGB image.