docs: fix truncate arguments (#19068)

* docs: truncate arg 'suffix' is string, not bool

* docs: fix required args for truncate

The arguments `ellipsis` and `suffix` are not required.
[Refer to VRL source](https://github.com/vectordotdev/vrl/blob/37319dfca17dc5d7637b24455199029cc30eb128/src/stdlib/truncate.rs#L48) to confirm.

website/cue/reference/remap/functions/truncate.cue

@@ -25,7 +25,7 @@ remap: functions: truncate: {
 				This argument is deprecated. An ellipsis (`...`) is appended if this is set to `true` _and_ the `value` string
 				ends up being truncated because it's exceeded the `limit`.
 				"""
-			required: true
+			required: false
 			type: ["boolean"]
 		},
 		{
@@ -34,8 +34,8 @@ remap: functions: truncate: {
 				A custom suffix (`...`) will be appended to truncated strings.
 				This is ignored if "ellipsis" is set to true for backwards compatibility.
 				"""
-			required: true
-			type: ["boolean"]
+			required: false
+			type: ["string"]
 		},
 	]
 	internal_failure_reasons: []