Update disclaimer about the standard library

Author: coolreader18

_config.yml

@@ -23,7 +23,7 @@ description: "An open source Python-3 (CPython >= 3.5.0) Interpreter written in
 # baseurl: "/" # the subpath of your site, e.g. /blog
 url: "https://rustpython.github.io" # the base hostname & protocol for your site, e.g. http://example.com
 github_username:  RustPython
-disclaimer: "RustPython is in a development phase and should not be used in production or a fault intolerant setting. Our current build supports only a subset of Python syntax."
+disclaimer: "RustPython is in a development phase and should not be used in production or a fault intolerant setting. Our current build supports only about half of the Python standard library."
 github: https://github.com/RustPython/RustPython/
 docs: https://github.com/RustPython/docs/
 gitter: https://gitter.im/rustpython/Lobby