[3.13] Use subcommand over sub-command in argparse docs (GH-142488) (#142588)

Use subcommand over sub-command in argparse docs (GH-142488)
(cherry picked from commit 387f88c)

Co-authored-by: Savannah Ostrowski <[email protected]>

Author: miss-islington

Doc/library/argparse.rst

@@ -1573,7 +1573,7 @@ The Namespace object
 Other utilities
 ---------------
 
-Sub-commands
+Subcommands
 ^^^^^^^^^^^^
 
 .. method:: ArgumentParser.add_subparsers(*, [title], [description], [prog], \
@@ -1602,7 +1602,7 @@ Sub-commands
    * *description* - description for the sub-parser group in help output, by
      default ``None``
 
-   * *prog* - usage information that will be displayed with sub-command help,
+   * *prog* - usage information that will be displayed with subcommand help,
      by default the name of the program and any positional arguments before the
      subparser argument
 
@@ -1612,7 +1612,7 @@ Sub-commands
    * action_ - the basic type of action to be taken when this argument is
      encountered at the command line
 
-   * dest_ - name of the attribute under which sub-command name will be
+   * dest_ - name of the attribute under which subcommand name will be
      stored; by default ``None`` and no value is stored
 
    * required_ - Whether or not a subcommand must be provided, by default