rel(1.2.2): Update changelog

Author: oesteban

doc/changelog/1.X.X-changelog

@@ -1,3 +1,13 @@
+1.2.2 (September 05, 2019)
+==========================
+
+  * FIX: Update mne.WatershedBEM command line (https://github.com/nipy/nipype/pull/3007)
+  * FIX: Specify correct stop criterion flag in PETPVC (https://github.com/nipy/nipype/pull/3010)
+  * ENH: Additional arguments to ANTs N4BiasFieldCorrection (https://github.com/nipy/nipype/pull/3012)
+  * ENH: Add ``--rescale-intensities`` and name_source to N4BiasFieldCorrection (https://github.com/nipy/nipype/pull/3011)
+  * ENH: Add index_mask_file input to ImageStats (https://github.com/nipy/nipype/pull/3005)
+  * MAINT: Add ``python_requires`` to package metadata (https://github.com/nipy/nipype/pull/3006)
+
 1.2.1 (August 19, 2019)
 =======================