all: fix some typos in comment

Change-Id: Ia209f0a6d9b19d14e655c65d1287a1416b48c487
Reviewed-on: https://go-review.googlesource.com/c/crypto/+/707535
Reviewed-by: Carlos Amedee <carlos@golang.org>
Reviewed-by: Michael Pratt <mpratt@google.com>
Auto-Submit: Sean Liao <sean@liao.dev>
Reviewed-by: Nicola Murino <nicola.murino@gmail.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Sean Liao <sean@liao.dev>

internal/wycheproof/rsa_pss_test.go

@@ -141,7 +141,7 @@ func TestRsaPss(t *testing.T) {
 			}
 			// Run all the tests twice: the first time with the salt length
 			// as PSSSaltLengthAuto, and the second time with the salt length
-			// explictily set to tg.SLen.
+			// explicitly set to tg.SLen.
 			for i := 0; i < 2; i++ {
 				for _, sig := range tg.Tests {
 					h.Reset()