[gcc r16-3661] doc: Document the -folding option for -fdump-tree-* [PR114892]

[Alex Coplan]

https://gcc.gnu.org/g:4f91825436c7377565a08a2f8cc4d22f8cc16317

commit r16-3661-g4f91825436c7377565a08a2f8cc4d22f8cc16317
Author: Alex Coplan <alex.coplan@arm.com>
Date:   Fri Sep 5 14:16:00 2025 +0000

    doc: Document the -folding option for -fdump-tree-* [PR114892]
    
    I noticed that the -fdump-tree-*-folding flag isn't documented in
    the Developer options section of invoke.texi; this patch fixes that.
    
    gcc/ChangeLog:
    
            PR tree-optimization/114892
            * doc/invoke.texi (Developer Options): Document -folding option
            for -fdump-tree-*.

Diff:
---
 gcc/doc/invoke.texi | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index b2a937fba355..85beda11c5c9 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -21275,6 +21275,9 @@ passes).
 @item note
 Enable other detailed optimization information (only available in
 certain passes).
+@item folding
+Enable dumping information about match-and-simplify (match.pd) patterns,
+when they are applied.
 @item all
 Turn on all options, except @option{raw}, @option{slim}, @option{verbose}
 and @option{lineno}.