The Python x.y docs describe the Python x.y language and stdlib, minus Idle (and turtledemo). The Python x.(y+1) What's New describes the delta between Python x.y and x.(y+1) in a user friendly and relevant way.

The Idle model of What's New type changes in every release does not fit the general model. For one thing, instead of all new non-bugfix changes appearing in .0 releases, there will be very few if any really new changes in x.(y+1).0. Almost all changes will have already appeared in some x.y.(z>0) release.

Whatever is supposed to be the situation with Idle news is not working right and would not be sufficient even it did.

What's New in 2.7 has this (and only this) about Idle:
---
PEP 434: IDLE Enhancement Exception for All Branches

PEP 434 describes a general exemption for changes made to the IDLE ...

For details of any IDLE changes, refer to the NEWS file for the specific release.
--
As near as I can tell, the general NEWS file is not easily accessible. So I think that should say 'Idle NEWS file ...., accessible through Help / About Idle'.

However, the 2.7 Idle news.txt file has not been updated since 2.7.5. Last year I suggested that Idle NEWS entries should begin in the idlelib file and be transferred to Misc/NEWS upon release. This was vetoed, and it was claimed that the transfer should and would happen the other way. It is not.

What's New 3.4 has only this about Idle: "Running IDLE with the -n flag (no subprocess) is deprecated. However, the feature will not be removed until issue 18823 is resolved."  For 3.4.1, nothing was added to Idle NEWS. Nothing was added after 3.3.0 either. The update on release is not happening.

Even if Idle news.txt were properly updated, it would not serve the purposes served by What's New and even the html changelog version of Misc/NEWS. The entries are disorganized, unfiltered, duplicated, tied to specific patches rather than user topics, begin with *unlinked* issue numbers, and say too little for the user.  

Unfiltered: most of the recent Idle news entries are about unittest and human test additions. Here is what I might put in a What's New document to cover them all.
---
Idle tests:

An automated unittest suite was started in May 2013. Users can run it with "python -m test -ugui test_idle". Adding "-v" will display the test classes and methods.

A human-operated test suite was started in May 2014. Uses can run it with "python -m idlelib.test_idle.htest. Report problems to the idle-dev mailing list.
---
There are other items that are also not relevant to normal users.

Duplication: if 3.4 news.txt were properly updated release by release, then the items listed for 3.5.0 would be the cumulative list added for 3.4.1 through 3.4.final, plus any 3.5-only user-relevant items that get added (there are none now).

This issue is about adding something that does not exist: an Idle specific file accessible from the idle help menu that it updated as needed with the occasional non-obvious user-relevant changes, especially those that users *need* to read.  An example of the latter is moving the the setting for the formatparagraph extension from config-main to confix-extensions (#20577).