Fix some documentation typos and improve a comment
diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
index 163ca38..e8f664a 100644
--- a/include/mbedtls/ssl.h
+++ b/include/mbedtls/ssl.h
@@ -2916,7 +2916,7 @@
*
* \return \c 0 if successful.
* \return #MBEDTLS_ERR_SSL_WANT_READ or #MBEDTLS_ERR_SSL_WANT_WRITE
- * in the handshake is incomplete but or waiting for data to
+ * if the handshake is incomplete and waiting for data to
* be available for reading from or writing to the underlying
* transport - in this case you must call this function again
* when the underlying transport is ready for the operation.
@@ -3018,10 +3018,10 @@
* \param len maximum number of bytes to read
*
* \return The (positive) number of bytes read if successful.
- * \return \c 0 is the read end of the underlying transport was closed
+ * \return \c 0 if the read end of the underlying transport was closed
* - in this case you must stop using the context (see below).
* \return #MBEDTLS_ERR_SSL_WANT_READ or #MBEDTLS_ERR_SSL_WANT_WRITE
- * in the handshake is incomplete but or waiting for data to
+ * if the handshake is incomplete and waiting for data to
* be available for reading from or writing to the underlying
* transport - in this case you must call this function again
* when the underlying transport is ready for the operation.
@@ -3098,7 +3098,7 @@
* \return The (non-negative) number of bytes actually written if
* successful (may be less than \p len).
* \return #MBEDTLS_ERR_SSL_WANT_READ or #MBEDTLS_ERR_SSL_WANT_WRITE
- * in the handshake is incomplete but or waiting for data to
+ * if the handshake is incomplete and waiting for data to
* be available for reading from or writing to the underlying
* transport - in this case you must call this function again
* when the underlying transport is ready for the operation.