Fix typos in documentation

CLA: trivial
Reviewed-by: NTim Hudson <tjh@openssl.org>
Reviewed-by: NMatthias St. Pierre <Matthias.St.Pierre@ncp-e.com>
(Merged from https://github.com/openssl/openssl/pull/7021)

doc/man3/BIO_s_file.pod

@@ -54,7 +54,7 @@ BIO_CLOSE, BIO_NOCLOSE (the close flag) BIO_FP_TEXT (sets the underlying
 stream to text mode, default is binary: this only has any effect under
 Win32).
 
-BIO_set_fp() set the fp of a file BIO to B<fp>. B<flags> has the same
+BIO_set_fp() sets the fp of a file BIO to B<fp>. B<flags> has the same
 meaning as in BIO_new_fp(), it is a macro.
 
 BIO_get_fp() retrieves the fp of a file BIO, it is a macro.

doc/man3/BN_generate_prime.pod

@@ -143,7 +143,7 @@ A callback is invoked through a call to B<BN_GENCB_call>. This will check
 the type of the callback and will invoke B<callback(a, b, gencb)> for new
 style callbacks or B<callback(a, b, cb_arg)> for old style.
 
-It is possible to obtained the argument associated with a BN_GENCB structure
+It is possible to obtain the argument associated with a BN_GENCB structure
 (set via a call to BN_GENCB_set or BN_GENCB_set_old) using BN_GENCB_get_arg.
 
 BN_generate_prime() (deprecated) works in the same way as

doc/man3/RSA_generate_key.pod

@@ -93,7 +93,7 @@ L<ERR_get_error(3)>, L<RAND_bytes(3)>, L<BN_generate_prime(3)>
 =head1 HISTORY
 
 RSA_generate_key() was deprecated in OpenSSL 0.9.8; use
-RSA_generate_key_ex() intsead.
+RSA_generate_key_ex() instead.
 
 =head1 COPYRIGHT