Update Preprocessing.md

docs/Preprocessing.md

@@ -3,7 +3,15 @@
 The preprocessing pipeline that is developed at the 
 [Berlin State Library](http://staatsbibliothek-berlin.de/) 
 comprises the following steps:
-- textline extraction @[sbb_pixelwise_segmentation](https://github.com/qurator-spk/pixelwise_segmentation_SBB)
-- OCR + word segmentation @[ocrd_tesserocr](https://github.com/OCR-D/ocrd_tesserocr)
+- Layout Analysis & Textline Extraction @[sbb_pixelwise_segmentation](https://github.com/qurator-spk/pixelwise_segmentation_SBB)
+- OCR & Word Segmentation @[ocrd_tesserocr](https://github.com/OCR-D/ocrd_tesserocr)
 - Tokenization
-- Pretagging @[sbb_ner](https://github.com/qurator-spk/sbb_ner)
+- Named Entity Recognition @[sbb_ner](https://github.com/qurator-spk/sbb_ner)
+
+### Layout Analysis & Textline Extraction
+
+### OCR & Word Segmentation
+
+### Tokenization
+
+### Named Entity Recognition