Fix some misuses of Sphinx roles and one typo
diff --git a/Doc/library/argparse.rst b/Doc/library/argparse.rst
index 38e52fb..88270ed 100644
--- a/Doc/library/argparse.rst
+++ b/Doc/library/argparse.rst
@@ -155,7 +155,7 @@
      conflicting optionals.
 
    * prog_ - The name of the program (default:
-     :data:`sys.argv[0]`)
+     ``sys.argv[0]``)
 
    * usage_ - The string describing the program usage (default: generated)