Update README.md

README.md

@@ -5,6 +5,9 @@ Library implements normalisation of HTML and plain parts of a MIME message.
 Normalisation strategies documentation:
 https://code.vereign.com/light/documentation/-/blob/master/Validation.md#normalization-strategies
 
+# Initialize project
+`yarn install`
+
 ## Testing
 
 HTML and text files with test cases provided in `__tests__/files`