Added preprocessing advices

README.md

@@ -452,6 +452,15 @@ future version.
 
 [Needs More Information]
 
+### Preprocessing advices
+
+- Filter out empty contents.
+- Remove unwanted references from the text, and replace either by the "references_text" or by the reference content itself.
+- Unescape HTML special characters: `import html; html.unescape(my_text)`
+- Remove superfluous line break in text.
+- Remove XML tags / replace by special tokens (<italic>, <sup>, <sub>, ...).
+- Join the items of the contents' lists.
+
 ## Additional Information
 
 ### Dataset Curators