docs: Various refinements ahead of launch

This is a series of changes across the documentation to improve the
overall first-user experience. Key changes:

  1. New "Express setup" section in the "Getting Started" page.
  2. Rename and reorder the left-hand menu bar components
  3. Fix various copyright dates
  4. Add presubmit animated gif to the pw_presubmit docs

Change-Id: I22a75ace8c2be15a6e5890d6e1b3618a1d53eefa

CODE_OF_CONDUCT.md

diff --git a/CODE_OF_CONDUCT.md b/CODE_OF_CONDUCT.md
index 7ff895c..551d804 100644
--- a/CODE_OF_CONDUCT.md
+++ b/CODE_OF_CONDUCT.md
@@ -1,4 +1,4 @@
-# Pigweed Code of Conduct
+# Code of Conduct
 
 ## Our Pledge