Convert some accidental refs to emphasis

GitOrigin-RevId: c35531c8b56cfbc0ac6c50a551c7974437881174
Change-Id: Iba25f112d6eac4278c7163a0a20352a77287e73a

code/png.py

diff --git a/code/png.py b/code/png.py
index 2afc3bc..3dbe34d 100755
--- a/code/png.py
+++ b/code/png.py
@@ -161,8 +161,8 @@
 when the bit depth is less than 8 (1, 2 and 4),
 several pixels are packed into each byte;
 when the bit depth is 16 each pixel value is decomposed into 2 bytes
-(and `packed` is a misnomer).
-This format is used by the :meth:`Writer.write_packed` method.
+(and *packed* is a misnomer).
+This format is used by the `Writer.write_packed` method.
 It isn't usually a convenient format,
 but may be just right if the source data for
 the PNG image comes from something that uses a similar format
@@ -1757,11 +1757,11 @@
     def read(self):
         """
         Read the PNG file and decode it.
-        Returns (`width`, `height`, `rows`, `info`).
+        Returns (*width*, *height*, *rows*, *info*).
 
         May use excessive memory.
 
-        `rows` is a sequence of rows;
+        *rows* is a sequence of rows;
         each row is a sequence of values.
         """