add note on available api/data files for peps

Author: JacobCoffee

README.rst

@@ -20,6 +20,17 @@ Shortcut redirects are also available.
 For example, ``https://peps.python.org/8`` redirects to the canonical link.
 
 
+API
+===
+
+Several data files are available at https://peps.python.org/api/:
+
+- ``peps.json``: All PEP metadata
+- ``release-cycle.json``: Python release cycle information
+- ``python-releases.json``: Complete Python release history
+- ``release-schedule.ics``: Python release dates in calendar format. 
+
+
 Contributing to PEPs
 ====================
 

peps/api/index.rst

@@ -207,3 +207,9 @@ for example:
        ]
      }
    }
+
+release-schedule.ics
+--------------------
+
+An iCalendar file of Python release dates is available at
+https://peps.python.org/api/release-schedule.ics.