Tweaks to editing api docs

Based on feedback from @tomdyson on #1310

docs/reference/pages/editing_api.rst

@@ -119,7 +119,7 @@ InlinePanel
 
     This panel allows for the creation of a "cluster" of related objects over a join to a separate model, such as a list of related links or slides to an image carousel.
 
-    This is a very powerful, but tricky feature which will take some space to cover, so we'll skip over it for now. For a full explanation on the usage of ``InlinePanel``, see :ref:`inline_panels`.
+    This is a poweful but complex feature which will take some space to cover, so we'll skip over it for now. For a full explanation on the usage of ``InlinePanel``, see :ref:`inline_panels`.
 
 FieldRowPanel
 -------------
@@ -130,7 +130,7 @@ FieldRowPanel
 
     Use of FieldRowPanel particularly helps reduce the "snow-blindness" effect of seeing so many fields on the page, for complex models. It also improves the perceived association between fields of a similar nature. For example if you created a model representing an "Event" which had a starting date and ending date, it may be intuitive to find the start and end date on the same "row".
 
-    FieldRowPanel should be used in combination with ``col*`` class names added to each of the child Panels of the FieldRowPanel. The Wagtail editing interface is laid out using a grid system, in which the maximum width of the editor is 12 columns wide. Classes ``col1``-``col12`` can be applied to each child of a FieldRowPanel. The class ``col3`` will ensure that field appears 3 columns wide or a quarter the width. ``col4`` would cause the field to be 4 columns wide, or a third the width.
+    FieldRowPanel should be used in combination with ``col*`` class names added to each of the child Panels of the FieldRowPanel. The Wagtail editing interface is laid out using a grid system, in which the maximum width of the editor is 12 columns. Classes ``col1``-``col12`` can be applied to each child of a FieldRowPanel. The class ``col3`` will ensure that field appears 3 columns wide or a quarter the width. ``col4`` would cause the field to be 4 columns wide, or a third the width.
 
     .. attribute:: FieldRowPanel.children
 
@@ -173,7 +173,7 @@ ImageChooserPanel
 
 .. class:: ImageChooserPanel(field_name)
 
-    One of the features of Wagtail is a unified image library, which you can access in your models through the ``Image`` model and the ``ImageChooserPanel`` chooser. Here's how:
+    Wagtail includes a unified image library, which you can access in your models through the ``Image`` model and the ``ImageChooserPanel`` chooser. Here's how:
 
     .. code-block:: python
 
@@ -194,7 +194,7 @@ ImageChooserPanel
               ImageChooserPanel('cover'),
           ]
 
-    Django's default behaviour is to "cascade" deletions through a ForeignKey relationship, which is probably not what you want happening. This is why the ``null``, ``blank``, and ``on_delete`` parameters should be set to allow for an empty field. (See `Django model field reference (on_delete)`_ ). ``ImageChooserPanel`` takes only one argument: the name of the field.
+    Django's default behaviour is to "cascade" deletions through a ForeignKey relationship, which may not be what you want. This is why the ``null``, ``blank``, and ``on_delete`` parameters should be set to allow for an empty field. (See `Django model field reference (on_delete)`_ ). ``ImageChooserPanel`` takes only one argument: the name of the field.
 
     .. _Django model field reference (on_delete): https://docs.djangoproject.com/en/dev/ref/models/fields/#django.db.models.ForeignKey.on_delete