Merge pull request #9499 from Carreau/document-raise-on-config

Document IPYTHON_SUPPRESS_CONFIG_ERRORS.

docs/source/development/config.rst

@@ -55,6 +55,19 b' under :file:`profile_default`. If you want the default config files for the'
 :mod:`IPython.parallel` applications, add ``--parallel`` to the end of the
 command-line args.
 
+.. note::
+
+    IPython configuration options are case sensitive, and IPython cannot
+    catch misnamed keys or invalid values.
+    
+    By default IPython will also ignore any invalid configuration files. 
+
+.. versionadded:: 5.0
+
+    IPython can be configured to abort in case of invalid configuration file.
+    To do so set the environment variable ``IPYTHON_SUPPRESS_CONFIG_ERRORS`` to
+    `'1'` or `'true'`
+
 
 Locating these files
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