Added note to README.md to indicate unofficial repository.

To help avoid confusion adding a note at the top of README.md file
to make it clear this is not the official SQLite repository.

Bug: 945204
Change-Id: Ie87b26685ff92a8745844526e6236a51ad1ff940
diff --git a/README.md b/README.md
index c12b77c..9ce130d 100644
--- a/README.md
+++ b/README.md
@@ -5,6 +5,11 @@
 are also included.  However, many other test scripts
 and most of the documentation are managed separately.
 
+**Note**: This is **not the official SQLite repository**. This repository is
+a fork of the [SQLite Git mirror](https://github.com/sqlite/sqlite.git) for
+the Chromium release branches of SQLite. If you are looking for the
+official SQLite source repository please visit [Fossil](https://www.fossil-scm.org/).
+
 ## Version Control
 
 SQLite sources are managed using the