Add MofNCompleteColumn ProgressColumn and Progress.get_default_column notes to docs

CHANGELOG.md

@@ -11,7 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Added ProgressColumn `MofNCompleteColumn` to display raw `completed/total` column (similar to DownloadColumn,
   but displays values as ints, does not convert to floats or add bit/bytes units). 
-  https://github.com/Textualize/rich/discussions/1899
+  https://github.com/Textualize/rich/pull/1941
 
 
 ## [11.2.0] - 2022-02-08

docs/source/progress.rst

@@ -113,12 +113,21 @@ The defaults are roughly equivalent to the following::
         TimeRemainingColumn(),
     )
 
+To create a Progress with your own columns in addition to the defaults, use :meth:`~rich.progress.Progress.get_default_columns`::
+
+    progress = Progress(
+        SpinnerColumn(),
+        *Progress.get_default_columns(),
+        TimeElapsedColumn(),
+    )
+
 The following column objects are available:
 
 - :class:`~rich.progress.BarColumn` Displays the bar.
 - :class:`~rich.progress.TextColumn` Displays text.
 - :class:`~rich.progress.TimeElapsedColumn` Displays the time elapsed.
 - :class:`~rich.progress.TimeRemainingColumn` Displays the estimated time remaining.
+- :class:`~rich.progress.MofNCompleteColumn` Displays completion progress as ``"{task.completed}/{task.total}"`` (works best if completed and total are ints).
 - :class:`~rich.progress.FileSizeColumn` Displays progress as file size (assumes the steps are bytes).
 - :class:`~rich.progress.TotalFileSizeColumn` Displays total file size (assumes the steps are bytes).
 - :class:`~rich.progress.DownloadColumn` Displays download progress (assumes the steps are bytes).
@@ -128,6 +137,7 @@ The following column objects are available:
 
 To implement your own columns, extend the :class:`~rich.progress.ProgressColumn` class and use it as you would the other columns.
 
+
 Table Columns
 ~~~~~~~~~~~~~