Add whatsnew entry.

Author: alexitkes

doc/source/whatsnew/v0.25.1.rst

@@ -7,6 +7,18 @@
 What's new in 0.25.1 (July XX, 2019)
 ------------------------------------
 
+.. warning::
+
+   Starting with the version 0.25.1, :func:`read_html` function
+   should get all its arguments but `io` and `match` as keyword
+   keyword only.
+
+.. warning::
+
+   Starting with the version 0.25.1, :func:`read_json` function
+   should get all its arguments but `path_or_buf` as keyword
+   arguments only.
+
 Enhancements
 ~~~~~~~~~~~~