[Docs] Add comprehensive CLI reference for all large vllm subcommands (#22601)

Signed-off-by: Harry Mellor <19981378+hmellor@users.noreply.github.com>

docs/cli/json_tip.inc.md

@@ -0,0 +1,9 @@
+When passing JSON CLI arguments, the following sets of arguments are equivalent:
+
+- `--json-arg '{"key1": "value1", "key2": {"key3": "value2"}}'`
+- `--json-arg.key1 value1 --json-arg.key2.key3 value2`
+
+Additionally, list elements can be passed individually using `+`:
+
+- `--json-arg '{"key4": ["value3", "value4", "value5"]}'`
+- `--json-arg.key4+ value3 --json-arg.key4+='value4,value5'`