UPSTREAM: Documentation/kbuild: Drop section numbers

Change the gendwarfksyms documentation to use proper chapter,
section, and subsection adornments instead of fragile section
numbers.

Suggested-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
(cherry picked from commit 881bf900)

Bug: 400972353
Link: https://lore.kernel.org/lkml/20250507231403.377725-11-samitolvanen@google.com/


Change-Id: I955ecc82274b613e67f08110052ee1401d638a24
Signed-off-by: Giuliano Procida <gprocida@google.com>
[jstultz: Switched to UPSTREAM]
Signed-off-by: John Stultz <jstultz@google.com>