Typo fix in comment.

(Thanks to William Hesse.)

Change-Id: I8479663250546a5ec0a024f80e50541f91d833bc
Reviewed-on: https://boringssl-review.googlesource.com/4020
Reviewed-by: David Benjamin <davidben@chromium.org>
Reviewed-by: Adam Langley <agl@google.com>

include/openssl/bio.h

diff --git a/include/openssl/bio.h b/include/openssl/bio.h
index 8ec321b..349a073 100644
--- a/include/openssl/bio.h
+++ b/include/openssl/bio.h
@@ -652,7 +652,7 @@
  * stack.
  *
  * The zero copy write operation is completed by calling
- * |BIO_zero_copy_write_buf_don|e. Neither |BIO_zero_copy_get_write_buf_done|
+ * |BIO_zero_copy_write_buf_done|. Neither |BIO_zero_copy_get_write_buf|
  * nor any other I/O write operation may be called while a zero copy write
  * operation is active. */
 OPENSSL_EXPORT int BIO_zero_copy_get_write_buf(BIO* bio,