Issue #28635: Drop the note that whatsnew is incomplete

(grafted from d12bc674b74eee73365e38fad1f170ed3349bd59)

Doc/whatsnew/3.6.rst

@@ -46,12 +46,6 @@
    This saves the maintainer the effort of going through the Mercurial log
    when researching a change.
 
-.. note::
-
-  Prerelease users should be aware that this document is currently in draft
-  form. It will be updated substantially as Python 3.6 moves towards release,
-  so it's worth checking back even after reading earlier versions.
-
 This article explains the new features in Python 3.6, compared to 3.5.
 
 .. seealso::
@@ -62,9 +56,6 @@ This article explains the new features in Python 3.6, compared to 3.5.
 Summary -- Release highlights
 =============================
 
-.. This section singles out the most important changes in Python 3.6.
-   Brevity is key.
-
 New syntax features:
 
 * :ref:`PEP 498 <whatsnew36-pep498>`, formatted string literals.