cmd/compile/internal/ir: fix a typo in node.go

README.md -> HACKING.md

Change-Id: I63909b86b2e6f8d9a34622f5d2b05048c79cd698
GitHub-Last-Rev: afaab8f
GitHub-Pull-Request: #50326
Reviewed-on: https://go-review.googlesource.com/c/go/+/374274
Run-TryBot: Dan Scales <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
Reviewed-by: Dan Scales <[email protected]>
Trust: Dan Scales <[email protected]>
Reviewed-by: Emmanuel Odeke <[email protected]>

Author: And-ZJ

src/cmd/compile/internal/ir/node.go

@@ -471,7 +471,7 @@ const (
 	UintptrEscapes              // pointers converted to uintptr escape
 
 	// Runtime-only func pragmas.
-	// See ../../../../runtime/README.md for detailed descriptions.
+	// See ../../../../runtime/HACKING.md for detailed descriptions.
 	Systemstack        // func must run on system stack
 	Nowritebarrier     // emit compiler error instead of write barrier
 	Nowritebarrierrec  // error on write barrier in this or recursive callees