Update README.md

Add a note on how to run this script locally

README.md

@@ -48,6 +48,15 @@ For full context and discussion on why this is needed, read the following two bl
          - `USER`: The username of the user whose followings you want to pull in (e.g. `michael` for the user `@michael@thms.uk`). Leave blank to disable this part of the script.
 4. Finally go to the Actions tab and enable the action. The action should now automatically run approximately once every 10 min. 
 
+### 3) Runn this script locally as a cron job
+
+If you want to, you can of course also run this script locally as a cron job:
+
+1. To get started, clone this repository. (If you'd rather not clone the full repository, you can simply download the `get_context.py` file, but don't forget to create a directory called `artifacts` in the same directory: The script expects this directory to be present, and stores information about posts it has already pushed into your instance in that directory, to avoid pushing the same posts over and over again.)
+2. Then simply run this script like so: `python3 get_context.py <ACCESS_TOKEN> <MASTODON_SERVER> <REPLY_INTERVAL_IN_HOURS> <HOME_TIMELINE_LENGTH> <MAX_FOLLOWINGS> <USER>` (the final two parameters can be omitted, if you are not interested).
+
+When setting up your cronjob, do make sure you are setting the interval long enough that two runs of the script don't overlap though! Running this script with overlapping will have unpleasant results ...
+
 ## Acknowledgments
 
 This script is mostly taken from [Abhinav Sarkar](https://notes.abhinavsarkar.net/2023/mastodon-context), with just some additions and alterations. Thank you Abhinav!