Fix docs.

Read Base64 encoded data from standard input and write the decoded

data to standard output:

 BIO *bio, *b64, bio_out;

 BIO *bio, *b64, *bio_out;

 char inbuf[512];

 int inlen;

 char message[] = "Hello World \n";

 b64 = BIO_new(BIO_f_base64());

 bio = BIO_new_fp(stdin, BIO_NOCLOSE);

 bio_out = BIO_new_fp(stdout, BIO_NOCLOSE);

 bio = BIO_push(b64, bio);

 while((inlen = BIO_read(bio, inbuf, strlen(message))) > 0) 

 while((inlen = BIO_read(bio, inbuf, 512) > 0) 

	BIO_write(bio_out, inbuf, inlen);

 BIO_free_all(bio);