Improve tree-sitter docs

Improve tree-sitter docs

* doc/lispref/positions.texi (List Motion): Incorporate more
accurate description of treesit-defun-type-regexp from
'(elisp) Tree-sitter Major Modes', replacing that duplicate
entry (bug#64018).

* doc/lispref/parsing.texi (Parsing Program Source)
(Language Grammar, Using Parser, Retrieving Nodes)
(Accessing Node Information, Pattern Matching, Multiple Languages):
(Tree-sitter Major Modes):
* doc/lispref/modes.texi (Parser-based Font Lock): Improve wording,
grammar, punctuation, and markup.  Fix typos.
(Parser-based Indentation): Ditto.  Document indent rule presets
field-is, catch-all, nth-sibling, grand-parent, and
great-grand-parent.

* lisp/treesit.el (treesit-simple-indent-presets): Mention field-is,
catch-all, nth-sibling, grand-parent, great-grand-parent in
docstring.
(treesit-major-mode-setup, treesit-explore-mode): Improve
docstring/commentary grammar.