crypto: revise wording about cryptographically broken algorithms

Updates text from https://golang.org/cl/42511

Updates #14395

Change-Id: I711100525e074ab360e577520280c37645db1c95
Reviewed-on: https://go-review.googlesource.com/42614Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
Reviewed-by: Rob Pike <r@golang.org>

src/crypto/des/const.go

@@ -6,7 +6,8 @@
 // Triple Data Encryption Algorithm (TDEA) as defined
 // in U.S. Federal Information Processing Standards Publication 46-3.
 //
-// DES is broken and should not be used anymore.
+// DES is cryptographically broken and should not be used for secure
+// applications.
 package des
 
 // Used to perform an initial permutation of a 64-bit input block.

src/crypto/md5/md5.go

@@ -6,7 +6,8 @@
 
 // Package md5 implements the MD5 hash algorithm as defined in RFC 1321.
 //
-// MD5 is broken and should not be used anymore.
+// MD5 is cryptographically broken and should not be used for secure
+// applications.
 package md5
 
 import (

src/crypto/rc4/rc4.go

@@ -5,7 +5,8 @@
 // Package rc4 implements RC4 encryption, as defined in Bruce Schneier's
 // Applied Cryptography.
 //
-// RC4 is broken and should not be used anymore.
+// RC4 is cryptographically broken and should not be used for secure
+// applications.
 package rc4
 
 import "strconv"

src/crypto/sha1/sha1.go

@@ -4,7 +4,8 @@
 
 // Package sha1 implements the SHA-1 hash algorithm as defined in RFC 3174.
 //
-// SHA-1 is broken and should not be used anymore.
+// SHA-1 is cryptographically broken and should not be used for secure
+// applications.
 package sha1
 
 import (