Remove readthedocs

GitOrigin-RevId: 9dadbb6572cde395b76f4395e5efbb3a9eee4da5
Change-Id: I2c07a9b4847927d6bdebf456810be84b7b7821f5

README.md

diff --git a/README.md b/README.md
index d76403a..1f711ee 100644
--- a/README.md
+++ b/README.md
@@ -8,7 +8,6 @@
 PNG module for Python. PyPNG is written entirely in Python.
 
 - PyPNG home page: https://gitlab.com/drj11/pypng/
-- PyPNG Documentation: https://pypng.readthedocs.io/en/latest/
 - PyPNG mailing list: https://groups.google.com/forum/#!forum/pypng-users