Add git command and warning

Author: Chicc

docs/intro.rst

@@ -22,6 +22,11 @@ is not provided. Python 2.7 or lower is not supported. Python 3.7 or lower is no
 Installing
 -----------
 
+**!!! IMPORTANT !!!** 
+For new features like options, buttons, and threads, you need to install from git until our v2.0 release on Jan 28th, 2021. ::
+
+    python3 -m pip install -U git+https://github.com/Pycord-Development/pycord
+
 You can get the library directly from PyPI: ::
 
     python3 -m pip install -U py-cord