Correct various documentation typos

Some of the documentation had the right explanation but the incorrect
function names attached.

Change-Id: I7b479dae6d71a5ac7bc86df5a3890508c3b3d09f
Reviewed-on: https://boringssl-review.googlesource.com/5090
Reviewed-by: Adam Langley <agl@google.com>
diff --git a/include/openssl/ssl.h b/include/openssl/ssl.h
index 97485c7..fa1a55d 100644
--- a/include/openssl/ssl.h
+++ b/include/openssl/ssl.h
@@ -2407,13 +2407,13 @@
 /* SSL_set_tmp_rsa returns one. */
 OPENSSL_EXPORT int SSL_set_tmp_rsa(SSL *ssl, const RSA *rsa);
 
-/* SSL_CTX_get_read_head returns zero. */
+/* SSL_CTX_get_read_ahead returns zero. */
 OPENSSL_EXPORT int SSL_CTX_get_read_ahead(const SSL_CTX *ctx);
 
 /* SSL_CTX_set_read_ahead does nothing. */
 OPENSSL_EXPORT void SSL_CTX_set_read_ahead(SSL_CTX *ctx, int yes);
 
-/* SSL_get_read_head returns zero. */
+/* SSL_get_read_ahead returns zero. */
 OPENSSL_EXPORT int SSL_get_read_ahead(const SSL *s);
 
 /* SSL_set_read_ahead does nothing. */