added Hacktoberfest content to readme.md (publiclab#10222)

* added Hacktoberfest content to readme.md

* Update README.md

moved Hacktober section further down

README.md

@@ -58,6 +58,7 @@ A full description of the features, audiences, inter-relationships, and goals of
 16. [Security](#security)
 17. [Developers](#developers)
 18. [First Time?](#first-time)
+19. [Hacktoberfest](#hacktoberfest)
 ****
 
 ## What makes this project different
@@ -265,6 +266,9 @@ New to open source/free software? Here is a selection of issues we've made **esp
 
 [Here](https://publiclab.org/notes/warren/11-22-2017/use-git-and-github-to-contribute-and-improve-public-lab-software) is a link to our Git workflow.
 
+## Hacktoberfest
+Wishing to contribute to Publiclab as part of Hacktoberfest? Check out our [Hacktoberfest contributing docs](https://github.com/publiclab/plots2/blob/main/HACKTOBERFEST.md)
+
 ## Let the code be with you.
 ### Happy opensourcing. :smile: