Fix typo in doc
diff --git a/include/polarssl/ssl.h b/include/polarssl/ssl.h
index 89e3375..2e33ffd 100644
--- a/include/polarssl/ssl.h
+++ b/include/polarssl/ssl.h
@@ -1118,7 +1118,7 @@
  *
  *                 If set, the PSK callback is called for each
  *                 handshake where a PSK ciphersuite was negotiated.
- *                 The callback provides the identity received and wants to
+ *                 The caller provides the identity received and wants to
  *                 receive the actual PSK data and length.
  *
  *                 The callback has the following parameters: (void *parameter,