Small smie.el doc and fix

* lisp/emacs-lisp/smie.el (smie-config-guess): Doc fix.
Explicit error if no grammar.
(smie-config-save): Doc fix.  Fix quote typo.

* etc/NEWS: Related edit.

1 files changed, 8 insertions, 3 deletions

diff --git a/etc/NEWS b/etc/NEWS
index d27f5655eb5..c1342ebfea1 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -896,9 +896,14 @@ All non-ancient Bash versions support this option.
 ---
 *** `sh-mode' now has its own setting for `add-log-current-defun-function'.
 
-** SMIE indentation can be customized via `smie-config'.
-Emacs can learn the appropriate indentation settings if you provide it
-with an indented sample file.
+** SMIE
+
+*** You can customize the indentation of modes that use SMIE via `smie-config'.
+The command `smie-config-guess' can help you derive the appropriate
+indentation settings, if you provide it with an indented sample file.
+Use `smie-config-save' to save the result.
+
+*** New commands `smie-config-show-indent' and `smie-config-set-indent'.
 
 ---
 ** SQL mode