crypto/rand: make documentation consistent between package comment and Reader

Updates #25959

Change-Id: I9ae64b216ab5807718db0db98b32de1dc5fa4bec
Reviewed-on: https://go-review.googlesource.com/119875Reviewed-by: Rob Pike <r@golang.org>
Reviewed-by: Filippo Valsorda <filippo@golang.org>

src/crypto/rand/rand.go

@@ -3,13 +3,13 @@
 // license that can be found in the LICENSE file.
 
 // Package rand implements a cryptographically secure
-// pseudorandom number generator.
+// random number generator.
 package rand
 
 import "io"
 
 // Reader is a global, shared instance of a cryptographically
-// strong pseudo-random generator.
+// secure random number generator.
 //
 // On Linux, Reader uses getrandom(2) if available, /dev/urandom otherwise.
 // On OpenBSD, Reader uses getentropy(2).