implement #2357

CONTRIBUTING.md

@@ -42,6 +42,7 @@ By contributing you agree to respect the [Code of Conduct](https://github.com/Eb
 - prefer atomic commits (one commit by addition/deletion/modification) over bigger commits. No need to squash your commits before submitting a PR. (We will never enforce this rule as it's just a matter of convenience for the maintainers)
 - if the book is older, include the publication date with the title. 
 - include the author name or names where appropriate. You can shorten author lists with "et al."
+- if the book is not finished, and is still being worked on, add the "in process" notation, as described [below.](#in_process)
 
 ### Formatting
 - All lists are `.md` files. Try to learn [Markdown](https://guides.github.com/features/mastering-markdown/) syntax. It's simple!
@@ -107,3 +108,10 @@ GOOD: * [Another Awesome Book](http://example.com/) - John Doe (HTML) [(PDF, EPU
 BAD: * [Another Awesome Book](http://example.com/book.html) - John Doe - 1970
 GOOD: * [Another Awesome Book (1970)](http://example.com/book.html) - John Doe
 ```
+
+<a name="in_process"></a>
+- In-process books 
+
+```
+* [Will Be Awesome Book](http://example.com/book.html) - John Doe (HTML) (:construction: *in process*)
+```