cmd/go: update link to RISC-V profile doc

The URL has changed.

Change-Id: I295020c59aaf64a89c4307fca527163095148a67
Reviewed-on: https://go-review.googlesource.com/c/go/+/591897
Reviewed-by: Joel Sing <[email protected]>
Reviewed-by: M Zhuo <[email protected]>
Reviewed-by: Dmitri Shuralyov <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Mark Ryan <[email protected]>

Author: cherrymui

src/cmd/go/alldocs.go

@@ -629,7 +629,7 @@ Architecture-specific environment variables:
 	GORISCV64
 		For GOARCH=riscv64, the RISC-V user-mode application profile for which
 		to compile. Valid values are rva20u64 (default), rva22u64.
-		See https://github.com/riscv/riscv-profiles/blob/main/profiles.adoc
+		See https://github.com/riscv/riscv-profiles/blob/main/src/profiles.adoc
 	GOWASM
 		For GOARCH=wasm, comma-separated list of experimental WebAssembly features to use.
 		Valid values are satconv, signext.