Document print_rich() in BBCode in RichTextLabel

While `print_rich()` works independently of RichTextLabel, it still
makes use of BBCode.

tutorials/ui/bbcode_in_richtextlabel.rst

@@ -1147,3 +1147,21 @@ This will add a few new BBCode commands, which can be used like so:
 
     [center][ghost]This is a custom [matrix]effect[/matrix][/ghost] made in
     [pulse freq=5.0 height=2.0][pulse color=#00FFAA freq=2.0]GDScript[/pulse][/pulse].[/center]
+
+Printing rich text to the console
+---------------------------------
+
+Using :ref:`print_rich<class_@GlobalScope_method_print_rich>`, you can print rich text to the editor Output
+panel and standard output (visible when the user runs the project from a terminal). This uses conversion
+to ANSI color codes.
+
+In the editor output, all BBCode tags are recognized as usual. In the terminal output, only a subset of
+BBCode tags will work, as documented in the linked ``print_rich()`` method description above.
+In the terminal, the colors will look different depending on the user's theme, while colors in the editor
+will use the same colors as they would in the project.
+
+.. note::
+
+    To print error and warning messages that can be filtered by type in the editor Output panel,
+    use :ref:`@GlobalScope.push_error<class_@GlobalScope_method_push_error>` and
+    :ref:`@GlobalScope.push_warning<class_@GlobalScope_method_push_warning>` instead of ``print_rich()``.