[PATCH] docs: Makefile: Sort Documentation targets case-insensitively in make help

[Bhanu Seshu Kumar Valluri <bhanuseshukumar@gmail.com>]

Avoid case-sensitive sorting when listing Documentation targets in make help.
Previously, targets like PCI and RCU appeared ahead of others due to uppercase
names.

Normalize casing during _SPHINXDIRS generation to ensure consistent and
intuitive ordering.

Fixes: 965fc39f7393 ("Documentation: sort _SPHINXDIRS for 'make help'")
Signed-off-by: Bhanu Seshu Kumar Valluri <bhanuseshukumar@gmail.com>
---
 Notes
 - Patch is tested with make help command.
 - Verified case-insensitive sorting.

 Documentation/Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Documentation/Makefile b/Documentation/Makefile
index 3609cb86137b..00c81e7947a9 100644
--- a/Documentation/Makefile
+++ b/Documentation/Makefile
@@ -23,7 +23,7 @@ SPHINXOPTS    =
 SPHINXDIRS    = .
 DOCS_THEME    =
 DOCS_CSS      =
-_SPHINXDIRS   = $(sort $(patsubst $(srctree)/Documentation/%/index.rst,%,$(wildcard $(srctree)/Documentation/*/index.rst)))
+_SPHINXDIRS   = $(shell printf "%s\n" $(patsubst $(srctree)/Documentation/%/index.rst,%,$(wildcard $(srctree)/Documentation/*/index.rst)) | sort -f)
 SPHINX_CONF   = conf.py
 PAPER         =
 BUILDDIR      = $(obj)/output
-- 
2.34.1