Update README.md

README.md

@@ -207,7 +207,14 @@ An example of "test" looks as follows
 
 #### Initial Data Collection and Normalization
 
-[More Information Needed]
+The datasets are chosen in accordance with the specified criteria. 
+First, domain variation: half of the datasets are chosen from different domains to ensure diversity, while the remaining half are from a single domain. 
+Another criterion is spelling orthographic mistakes:
+the datasets exclusively comprised mistyping, omitting grammatical or more complex errors of nonnative speakers.
+- **RUSpellRU**: texts collected from ([LiveJournal](https://www.livejournal.com/media)), with manually corrected typos and errors;
+- **MultidomainGold**: examples from 7 text sources, including the open web, news, social media, reviews, subtitles, policy documents and literary works;
+- **MedSpellChecker**: texts with errors from medical anamnesis;
+- **GitHubTypoCorpusRu**: spelling errors and typos in commits from [GitHub](https://github.com);
 
 #### Who are the source language producers?