Fix parameter name in documentation of ECDH module
diff --git a/include/mbedtls/ecdh.h b/include/mbedtls/ecdh.h
index 6f7ae7a..f17446c 100644
--- a/include/mbedtls/ecdh.h
+++ b/include/mbedtls/ecdh.h
@@ -283,9 +283,9 @@
* \see ecp.h
*
* \param ctx The ECDHE context to use. This must be initialized.
- * \param p On input, *p must be the start of the input buffer.
- * On output, *p is updated to point to the end of the data
- * that has been read. On success, this is the first byte
+ * \param buf On input, \c *buf must be the start of the input buffer.
+ * On output, \c *buf is updated to point to the end of the
+ * data that has been read. On success, this is the first byte
* past the end of the ServerKeyExchange parameters.
* On error, this is the point at which an error has been
* detected, which is usually not useful except to debug