tweak doc a little to reduce onboarding friction for thread-users

core/prof/spall/doc.odin

@@ -1,8 +1,9 @@
 /*
 	import "core:prof/spall"
+	import "core:sync"
 
 	spall_ctx: spall.Context
-	spall_buffer: spall.Buffer
+	@(thread_local) spall_buffer: spall.Buffer
 
 	foo :: proc() {
 		spall.SCOPED_EVENT(&spall_ctx, &spall_buffer, #procedure)
@@ -13,7 +14,7 @@
 		defer spall.context_destroy(&spall_ctx)
 
 		buffer_backing := make([]u8, spall.BUFFER_DEFAULT_SIZE)
-		spall_buffer = spall.buffer_create(buffer_backing)
+		spall_buffer = spall.buffer_create(buffer_backing, sync.current_thread_id)
 		defer spall.buffer_destroy(&spall_ctx, &spall_buffer)
 
 		spall.SCOPED_EVENT(&spall_ctx, &spall_buffer, #procedure)