Add basic cron instructions

Author: nthapaliya

README.md

@@ -13,3 +13,18 @@ sudo easy_install pip
 sudo pip install --upgrade pip
 pip install requests
 ```
+
+## Optional: Scheduling via `crontab`
+
+If you wish to schedule the script to run at specific intervals,
+you have to set up a cron job.
+
+1) Decide the frequency at which you want to run the script and note the cron
+   expression for it. For example, if you want to run it every hour, 
+   the cron expression would look like "0 * * * *".  
+   Use https://crontab.guru/ as reference.
+2) Run `crontab -e` to edit the cron file.
+3) Put in a new line: `<crontab expression> <full path to python> <full path to script>`  
+   For example, a new line could be `30 * * * * /usr/bin/python /Users/johndoe/projects/bamboo_to_officespace.py`  
+   Save the file and exit the editor.
+4) `crontab -l` to check if the new settings apply. You should see the latest task in the list.