Docs updates

- Update docs copyright.
- Remove duplicate title in index.rst.
- Update note about Python 2 compatibility, since most Pigweed code
  requires Python 3.

Change-Id: I9c61a55c622b162317ab7fc4c5eec5fdf292bb02
diff --git a/docs/index.rst b/docs/index.rst
index 80157ad..7643e4d 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -2,17 +2,13 @@
 
 .. highlight:: sh
 
-====
-Home
-====
-
 .. mdinclude:: README.md
 
 .. toctree::
   :maxdepth: 1
   :hidden:
 
-  self
+  Home <self>
   docs/embedded_cpp_guide
   docs/style_guide
   targets