wamr: bump the default stack guard size

using 0 by default seems a bit too aggressive to me.

1024 here is what would have been used before this kconfig knob
was introduced by #1259.
It also matches some expectations in the recent wamrc.
https://github.com/bytecodealliance/wasm-micro-runtime/blob/40b430fd240ad45f5c7a7dd0239fa2425e7c294e/core/iwasm/compilation/aot_emit_aot_file.c#L2672-L2678

Author: yamt

interpreters/wamr/Kconfig

@@ -103,10 +103,18 @@ config INTERPRETERS_WAMR_ENABLE_SPEC_TEST
 
 config INTERPRETERS_WAMR_STACK_GUARD_SIZE
 	int "Custom stack guard size"
-	default 0
+	default 1024
 	---help---
-		Reserve some space in stack as guard to detect stack overflow,
-		use stack base by default but may not safe enough.
+		Reserve some space in stack as guard to detect stack overflow.
+
+		Please consider this extra stack consumption when deciding the stack
+		size of your NuttX task on which you run WAMR.
+
+		The default value here (1024) was chosen to match the default value on
+		the majority of other platforms, including Linux. It also matches
+		the expections in the WAMR AoT compiler.
+		On the other hand, it might be a bit larger than what's strictly
+		necessary, especially for typical NuttX targets.
 
 config INTERPRETERS_WAMR_THREAD_MGR
 	bool "Enable thread manager"