Document easy ways of typing undo key on TTY frames

* doc/emacs/basic.texi (Basic Undo): Document the easiest way to
type the undo key.

* etc/tutorials/TUTORIAL: Describe typing C-_ without the Shift
key.

1 files changed, 1 insertions, 0 deletions

diff --git a/etc/tutorials/TUTORIAL b/etc/tutorials/TUTORIAL
index 227c13f3e3a..319ba52b670 100644
--- a/etc/tutorials/TUTORIAL
+++ b/etc/tutorials/TUTORIAL
@@ -473,6 +473,7 @@ to undo insertion of text.)
 >> Kill this line with C-k, then type C-/ and it should reappear.
 
 C-_ is an alternative undo command; it works exactly the same as C-/.
+On some text terminals, you can omit the shift key when you type C-_.
 On some text terminals, typing C-/ actually sends C-_ to Emacs.
 Alternatively, C-x u also works exactly like C-/, but is a little less
 convenient to type.