Collaboration request added

Added in 10- a note how people can collaborate

sections/08-InterviewQuestions.md

@@ -1,6 +1,13 @@
 1001 Data Engineering Interview Questions
 =========================================
 
+Hey everyone, this collection of questions and answers is a work in progress.
+I'm going to keep adding Q&As, but you are invited to collaborate through GitHub:
+- Eiter clone this repo, make your changes and create a pull request
+- or raise an issue on GitHub with your questions and answers and we'll add them
+
+Andreas
+
 ## Contents:
 
 - [Python](10-InterviewQuestions.md#python)