#20295: Teach imghdr to recognize OpenEXR format images.

Patch by Martin Vignali, test by Claudiu Popa.
diff --git a/Doc/library/imghdr.rst b/Doc/library/imghdr.rst
index 06faa88..c60df24 100644
--- a/Doc/library/imghdr.rst
+++ b/Doc/library/imghdr.rst
@@ -50,6 +50,11 @@
 +------------+-----------------------------------+
 | ``'webp'`` | WebP files                        |
 +------------+-----------------------------------+
+| ``'exr'``  | OpenEXR Files                     |
++------------+-----------------------------------+
+
+.. versionadded:: 3.5
+   The *exr* format was added.
 
 .. versionchanged:: 3.5
    The *webp* type was added.