runtime(json5): add basic indent support (#14298)

Signed-off-by: Rocco Mao <dapeng.mao@qq.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/indent/json5.vim b/runtime/indent/json5.vim
new file mode 100644
index 0000000..5977a4b
--- /dev/null
+++ b/runtime/indent/json5.vim
@@ -0,0 +1,11 @@
+" Vim indent file
+" Language:     JSON5
+" Maintainer:   The Vim Project <https://github.com/vim/vim>
+" Last Change:  2024-03-26
+
+if exists("b:did_indent")
+  finish
+endif
+
+" Same as jsonc indenting for now
+runtime! indent/jsonc.vim