Consolidate What's new dev and 5.5

Need to be backported to 5.x branch.

docs/source/whatsnew/development.rst

@@ -10,6 +10,49 b' This document describes in-flight development work.'
     conflicts for other Pull Requests). Instead, create a new file in the
     `docs/source/whatsnew/pr` folder
 
+IPython 6.2 contains all the bugs fixes and features available in IPython 5.5:
+
+ - Built in progress bar support
+ - System Wide config
+
+As well as the following:
+
+
+Function signature
+------------------
+
+Terminal IPython will now show the signature of the function while completing.
+Only the currently highlighted function will show its signature on the line
+below the completer by default. The functionality is recent so might be
+limited, we welcome bug report and enhancement request on it. :gh:`10507`
+
+Assignments return values
+-------------------------
+
+IPython can now trigger the display hook on last assignment of cells. 
+Up until 6.0 the following code wouldn't show the value of the assigned
+variable::
+
+    In[1]: xyz = "something"
+    # nothing shown
+
+You would have to actually make it the last statement::
+
+    In [2]: xyz = "something else"
+    ...   : xyz
+    Out[2]: "something else"
+
+With the option ``InteractiveShell.ast_node_interactivity='last_expr_or_assign'``
+you can now do::
+
+    In [2]: xyz = "something else"
+    Out[2]: "something else"
+
+This option can be toggled at runtime with the ``%config`` magic, and will
+trigger on assignment ``a = 1``, augmented assignment ``+=``, ``-=``, ``|=`` ...
+as well as type annotated assignments: ``a:int = 2``.
+
+See :gh:`10598`
 
 
 .. DO NOT EDIT THIS LINE BEFORE RELEASE. FEATURE INSERTION POINT.

docs/source/whatsnew/index.rst

@@ -20,7 +20,7 b' development work they do here in a user friendly format.'
 .. toctree::
    :maxdepth: 1
 
-   developement
+   development
    version6
    github-stats-6
    version5

docs/source/whatsnew/version5.rst

@@ -4,6 +4,36 b''
 
 .. _whatsnew540:
 
+IPython 5.5
+===========
+
+System Wide config
+------------------
+
+- IPython now looks for config files in ``{sys.prefix}/etc/ipython``
+  for environment-specific configuration.
+- Startup files can be found in ``/etc/ipython/startup`` or ``{sys.prefix}/etc/ipython/startup``
+  in addition to the profile directory, for system-wide or env-specific startup files.
+
+See :gh:`10644`
+
+ProgressBar
+-----------
+
+
+IPython now has built-in support for progressbars::
+
+    In[1]: from IPython.display import ProgressBar
+    ...  : pb = ProgressBar(100)
+    ...  : pb
+
+    In[2]: pb.progress = 50
+
+    # progress bar in cell 1 updates.
+
+See :gh:`10755`
+
+
 IPython 5.4
 ===========