Add docstrings for getixif() and Exif

src/PIL/Image.py

@@ -1432,6 +1432,11 @@ class Image:
             return {get_name(root.tag): get_value(root)}
 
     def getexif(self):
+        """
+        Gets EXIF data of the image.
+        
+        :returns: an :py:class:`~PIL.Image.Exif` object.
+        """
         if self._exif is None:
             self._exif = Exif()
             self._exif._loaded = False
@@ -3601,6 +3606,20 @@ atexit.register(core.clear_cache)
 
 
 class Exif(MutableMapping):
+    """
+    Exif class provides read and write access to EXIF image data.
+    
+    Only basic information is available on the root level, in Exif object
+    itself. In order to access the rest, obtain their respective IFDs using
+    :py:meth:`~PIL.Image.Exif.get_ifd` method and one of
+    :py:class:`~PIL.ExifTags.IFD` members (most notably `Exif` and
+    `GPSInfo`).
+    
+    Both root Exif and child IFD objects support dict interface and can be
+    indexed by int values that are available as enum members of
+    :py:class:`~PIL.ExifTags.Base`, :py:class:`~PIL.ExifTags.GPS`, and
+    :py:class:`~PIL.ExifTags.Interop`.
+    """
     endian = None
     bigtiff = False