Language correction

Author: myheroyuki

doc/usage.rst

@@ -40,7 +40,7 @@ Alternatively you can use :py:meth:`rsa.PrivateKey.load_pkcs1` and
     ...     keydata = privatefile.read()
     >>> privkey = rsa.PrivateKey.load_pkcs1(keydata)
 
-PKCS#1 v2.1 allows you to generate RSA keys with multiple primes:
+Python-RSA also allows you to generate RSA keys with multiple primes:
 
     >>> import rsa
     >>> (pubkey, privkey) = rsa.newkeys(512, nprimes=3)