Reword API change doc

Author: aitikgupta

doc/api/next_api_changes/behavior/20367-AG.rst

@@ -1,12 +1,12 @@
-``Text``
-~~~~~~~~
+``Text`` allows a boolean *parse_math*
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-``Text`` objects now allow a **parse_math** keyword-only argument
+`.Text` objects now allow a *parse_math* keyword-only argument
 which defaults to True. When it is passed as False, that text object
 will consider the string as a literal and will not try to parse it
 as a mathtext object.
 
-``TextBox``
------------
-``TextBox`` now defaults its text object's **parse_math** argument
+``TextBox`` defaults it to False
+--------------------------------
+`.TextBox` now defaults its text object's *parse_math** argument
 as False.