Document tree-sitter features in the user manual

* lisp/progmodes/c-ts-mode.el (c-ts-mode-map): Bind "C-c .", for
consistency with CC mode.
* lisp/treesit.el (treesit-font-lock-level): Doc fix.

* doc/emacs/programs.texi (C Indent, Custom C Indent): Document
the indentation features of 'c-ts-mode'.
(Moving by Defuns): Document 'treesit-defun-tactic'.
* doc/emacs/files.texi (Visiting): Document
'treesit-max-buffer-size'.
* doc/emacs/display.texi (Traditional Font Lock)
(Parser-based Font Lock): New subsections.
* doc/emacs/emacs.texi (Top): Update top-level menu.

1 files changed, 11 insertions, 0 deletions

diff --git a/doc/emacs/files.texi b/doc/emacs/files.texi
index 6d666831612..c0e702da947 100644
--- a/doc/emacs/files.texi
+++ b/doc/emacs/files.texi
@@ -215,6 +215,17 @@ by the integers that Emacs can represent (@pxref{Buffers}).  If you
 try, Emacs displays an error message saying that the maximum buffer
 size has been exceeded.
 
+@vindex treesit-max-buffer-size
+  If you try to visit a file whose major mode (@pxref{Major Modes})
+uses the tree-sitter parsing library, Emacs will display a warning if
+the file's size in bytes is larger than the value of the variable
+@code{treesit-max-buffer-size}.  The default value is 40 megabytes for
+64-bit Emacs and 15 megabytes for 32-bit Emacs.  This avoids the
+danger of having Emacs run out of memory by preventing the activation
+of major modes based on tree-sitter in such large buffers, because a
+typical tree-sitter parser needs about 10 times as much memory as the
+text it parses.
+
 @cindex wildcard characters in file names
 @vindex find-file-wildcards
   If the file name you specify contains shell-style wildcard